diff --git a/regtest/contour/rt-parse-only/shortcuts.json.reference b/regtest/contour/rt-parse-only/shortcuts.json.reference
index fe7a825394..e58a079ef5 100644
--- a/regtest/contour/rt-parse-only/shortcuts.json.reference
+++ b/regtest/contour/rt-parse-only/shortcuts.json.reference
@@ -13,7 +13,7 @@
    },
    "fcc" : {
       "defaults" : " PHI=0.0 THETA=0.0 PSI=0.0",
-      "expansion" : "fcc_grp: GROUP ATOMS=1-5184 \nfcc_mat: CONTACT_MATRIX GROUP=1-5184 SWITCH={CUBIC D_0=1.2 D_MAX=1.5} COMPONENTS \nfcc_vfunc: FCCUBIC_FUNC ARG=fcc_mat.x,fcc_mat.y,fcc_mat.z ALPHA=27 \nfcc_wvfunc: CUSTOM ARG=fcc_vfunc,fcc_mat.w FUNC=x*y PERIODIC=NO \nfcc_ones: ONES SIZE=5184\nfcc: MATRIX_VECTOR_PRODUCT ARG=fcc_wvfunc,fcc_ones \nfcc_denom: MATRIX_VECTOR_PRODUCT ARG=fcc_mat.w,fcc_ones \nfcc_n: CUSTOM ARG=fcc,fcc_denom FUNC=x/y PERIODIC=NO "
+      "expansion" : "fcc_grp: GROUP ATOMS=1-5184 \nfcc_mat: CONTACT_MATRIX GROUP=1-5184 SWITCH={CUBIC D_0=1.2 D_MAX=1.5} COMPONENTS \nfcc_vfunc: FCCUBIC_FUNC ARG=fcc_mat.x,fcc_mat.y,fcc_mat.z ALPHA=27\nfcc_wvfunc: CUSTOM ARG=fcc_vfunc,fcc_mat.w FUNC=x*y PERIODIC=NO\nfcc_ones: ONES SIZE=5184\nfcc: MATRIX_VECTOR_PRODUCT ARG=fcc_wvfunc,fcc_ones\nfcc_denom: MATRIX_VECTOR_PRODUCT ARG=fcc_mat.w,fcc_ones\nfcc_n: CUSTOM ARG=fcc,fcc_denom FUNC=x/y PERIODIC=NO"
    },
    "ones" : {
       "expansion" : "ones: CONSTANT NOLOG VALUES=1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1"
diff --git a/regtest/multicolvar/rt-parse-only/shortcuts.json.reference b/regtest/multicolvar/rt-parse-only/shortcuts.json.reference
index 4bcac5ad12..0b9b15e922 100644
--- a/regtest/multicolvar/rt-parse-only/shortcuts.json.reference
+++ b/regtest/multicolvar/rt-parse-only/shortcuts.json.reference
@@ -1,5 +1,5 @@
 {
    "dallk" : {
-      "expansion" : "dallk_vatom1: CENTER ATOMS=1,2 \ndallk_vatom2: CENTER ATOMS=3,4 \ndallk_vatom3: CENTER ATOMS=5,6 \ndallk_grp: GROUP ATOMS=dallk_vatom1,dallk_vatom2,dallk_vatom3 \ndallk: DISTANCE ATOMS1=1,2 ATOMS2=3,4 ATOMS3=5,6 \ndallk_lt1: LESS_THAN ARG=dallk SWITCH={RATIONAL R_0=1.0} \ndallk_lessthan-1: SUM ARG=dallk_lt1 PERIODIC=NO \ndallk_lt2: LESS_THAN ARG=dallk SWITCH={RATIONAL R_0=1.5} \ndallk_lessthan-2: SUM ARG=dallk_lt2 PERIODIC=NO \ndallk_lowest: LOWEST ARG=dallk \ndallk_mean: MEAN ARG=dallk PERIODIC=NO "
+      "expansion" : "dallk_vatom1: CENTER ATOMS=1,2 \ndallk_vatom2: CENTER ATOMS=3,4 \ndallk_vatom3: CENTER ATOMS=5,6 \ndallk_grp: GROUP ATOMS=dallk_vatom1,dallk_vatom2,dallk_vatom3 \ndallk: DISTANCE ATOMS1=1,2 ATOMS2=3,4 ATOMS3=5,6 \ndallk_lt1: LESS_THAN ARG=dallk SWITCH={RATIONAL R_0=1.0}\ndallk_lessthan-1: SUM ARG=dallk_lt1 PERIODIC=NO\ndallk_lt2: LESS_THAN ARG=dallk SWITCH={RATIONAL R_0=1.5}\ndallk_lessthan-2: SUM ARG=dallk_lt2 PERIODIC=NO\ndallk_lowest: LOWEST ARG=dallk\ndallk_mean: MEAN ARG=dallk PERIODIC=NO"
    }
 }
diff --git a/regtest/symfunc/rt-parse-only/shortcuts.json.reference b/regtest/symfunc/rt-parse-only/shortcuts.json.reference
index 99c54df990..eafdeee381 100644
--- a/regtest/symfunc/rt-parse-only/shortcuts.json.reference
+++ b/regtest/symfunc/rt-parse-only/shortcuts.json.reference
@@ -1,5 +1,5 @@
 {
    "q1" : {
-      "expansion" : "q1_grp: GROUP ATOMS=1-10 \nq1_mat: CONTACT_MATRIX GROUP=1-10 SWITCH={RATIONAL R_0=1} COMPONENTS \nq1_sh: SPHERICAL_HARMONIC ARG=q1_mat.x,q1_mat.y,q1_mat.z,q1_mat.w L=1 \nq1_denom_ones: ONES SIZE=10\nq1_denom: MATRIX_VECTOR_PRODUCT ARG=q1_mat.w,q1_denom_ones \nq1_sp: MATRIX_VECTOR_PRODUCT ARG=q1_sh.*,q1_denom_ones \nq1_norm2: COMBINE PERIODIC=NO POWERS=2,2,2,2,2,2 ARG=q1_sp.rm-n1,q1_sp.im-n1,q1_sp.rm-0,q1_sp.im-0,q1_sp.rm-p1,q1_sp.im-p1 \nq1_norm: CUSTOM ARG=q1_norm2 FUNC=sqrt(x) PERIODIC=NO \nq1: CUSTOM ARG=q1_norm,q1_denom FUNC=x/y PERIODIC=NO "
+      "expansion" : "q1_grp: GROUP ATOMS=1-10 \nq1_mat: CONTACT_MATRIX GROUP=1-10 SWITCH={RATIONAL R_0=1} COMPONENTS \nq1_sh: SPHERICAL_HARMONIC ARG=q1_mat.x,q1_mat.y,q1_mat.z,q1_mat.w L=1\nq1_denom_ones: ONES SIZE=10\nq1_denom: MATRIX_VECTOR_PRODUCT ARG=q1_mat.w,q1_denom_ones\nq1_sp: MATRIX_VECTOR_PRODUCT ARG=q1_sh.*,q1_denom_ones\nq1_norm2: COMBINE PERIODIC=NO POWERS=2,2,2,2,2,2 ARG=q1_sp.rm-n1,q1_sp.im-n1,q1_sp.rm-0,q1_sp.im-0,q1_sp.rm-p1,q1_sp.im-p1\nq1_norm: CUSTOM ARG=q1_norm2 FUNC=sqrt(x) PERIODIC=NO\nq1: CUSTOM ARG=q1_norm,q1_denom FUNC=x/y PERIODIC=NO"
    }
 }
diff --git a/regtest/wham/rt-parse-only/shortcuts.json.reference b/regtest/wham/rt-parse-only/shortcuts.json.reference
index d8dc2e5683..5dfdc0220f 100644
--- a/regtest/wham/rt-parse-only/shortcuts.json.reference
+++ b/regtest/wham/rt-parse-only/shortcuts.json.reference
@@ -1,7 +1,7 @@
 {
    "hh" : {
       "defaults" : " STRIDE=1",
-      "expansion" : "hh_gather: GATHER_REPLICAS ARG=rp.bias\nhh_gatherv: CONCATENATE ARG=hh_gather.*\nhh_collect: COLLECT TYPE=vector ARG=hh_gatherv STRIDE=1 \nhh_wham: WHAM ARG=hh_collect TEMP=300\nhh_data_phi: COLLECT ARG=phi \nhh: KDE ARG=hh_data_phi HEIGHTS=hh_wham KERNEL=DISCRETE GRID_MIN=-pi GRID_MAX=pi GRID_BIN=50 "
+      "expansion" : "hh_gather: GATHER_REPLICAS ARG=rp.bias\nhh_gatherv: CONCATENATE ARG=hh_gather.*\nhh_collect: COLLECT TYPE=vector ARG=hh_gatherv STRIDE=1\nhh_wham: WHAM ARG=hh_collect TEMP=300\nhh_data_phi: COLLECT ARG=phi\nhh: KDE  ARG=hh_data_phi HEIGHTS=hh_wham KERNEL=DISCRETE GRID_MIN=-pi GRID_MAX=pi GRID_BIN=50"
    },
    "rp" : {
       "defaults" : " SLOPE=0.0"
diff --git a/src/adjmat/AdjacencyMatrixBase.cpp b/src/adjmat/AdjacencyMatrixBase.cpp
index a97bc0fb8a..3e9d6f3e8c 100644
--- a/src/adjmat/AdjacencyMatrixBase.cpp
+++ b/src/adjmat/AdjacencyMatrixBase.cpp
@@ -28,7 +28,7 @@ namespace PLMD {
 namespace adjmat {
 
 void AdjacencyMatrixBase::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords( keys ); keys.remove("ARG");
+  ActionWithMatrix::registerKeywords( keys );
   keys.add("atoms","GROUP","the atoms for which you would like to calculate the adjacency matrix");
   keys.add("atoms","GROUPA","");
   keys.add("atoms","GROUPB","");
diff --git a/src/adjmat/Neighbors.cpp b/src/adjmat/Neighbors.cpp
index 1e5b8240c7..b56465d836 100644
--- a/src/adjmat/Neighbors.cpp
+++ b/src/adjmat/Neighbors.cpp
@@ -52,7 +52,8 @@ class Neighbors : public ActionWithMatrix {
 PLUMED_REGISTER_ACTION(Neighbors,"NEIGHBORS")
 
 void Neighbors::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords( keys ); keys.use("ARG");
+  ActionWithMatrix::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","matrix","the label of an adjacency/distance matrix that will be used to find the nearest neighbors");
   keys.add("compulsory","NLOWEST","0","in each row of the output matrix set the elements that correspond to the n lowest elements in each row of the input matrix equal to one");
   keys.add("compulsory","NHIGHEST","0","in each row of the output matrix set the elements that correspond to the n highest elements in each row of the input matrix equal to one");
   keys.setValueDescription("matrix","a matrix in which the ij element is one if the ij-element of the input matrix is one of the NLOWEST/NHIGHEST elements on that row of the input matrix and zero otherwise");
diff --git a/src/adjmat/TorsionsMatrix.cpp b/src/adjmat/TorsionsMatrix.cpp
index 39d736a03c..2815d818e8 100644
--- a/src/adjmat/TorsionsMatrix.cpp
+++ b/src/adjmat/TorsionsMatrix.cpp
@@ -52,7 +52,8 @@ class TorsionsMatrix : public ActionWithMatrix {
 PLUMED_REGISTER_ACTION(TorsionsMatrix,"TORSIONS_MATRIX")
 
 void TorsionsMatrix::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords(keys); keys.use("ARG");
+  ActionWithMatrix::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","matrix","an Nx3 and a 3xN matrix that contain the bond vectors that you would like to determine the torsion angles between");
   keys.add("atoms","POSITIONS1","the positions to use for the molecules specified using the first argument");
   keys.add("atoms","POSITIONS2","the positions to use for the molecules specified using the second argument");
   keys.setValueDescription("matrix","the matrix of torsions between the two vectors of input directors");
diff --git a/src/annfunc/ANN.cpp b/src/annfunc/ANN.cpp
index b18d63978f..7b97739b20 100644
--- a/src/annfunc/ANN.cpp
+++ b/src/annfunc/ANN.cpp
@@ -111,7 +111,7 @@ PLUMED_REGISTER_ACTION(ANN,"ANN")
 
 void ANN::registerKeywords( Keywords& keys ) {
   Function::registerKeywords(keys);
-  keys.use("ARG"); keys.use("PERIODIC");
+  keys.use("PERIODIC");
   keys.add("compulsory", "NUM_LAYERS", "number of layers of the neural network");
   keys.add("compulsory", "NUM_NODES", "numbers of nodes in each layer of the neural network");
   keys.add("compulsory", "ACTIVATIONS", "activation functions for the neural network");
diff --git a/src/bias/ABMD.cpp b/src/bias/ABMD.cpp
index 24e0295d85..7923208a11 100644
--- a/src/bias/ABMD.cpp
+++ b/src/bias/ABMD.cpp
@@ -96,7 +96,6 @@ PLUMED_REGISTER_ACTION(ABMD,"ABMD")
 
 void ABMD::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","TO","The array of target values");
   keys.add("compulsory","KAPPA","The array of force constants.");
   keys.add("optional","MIN","Array of starting values for the bias (set rho_m(t), otherwise it is set using the current value of ARG)");
diff --git a/src/bias/Bias.cpp b/src/bias/Bias.cpp
index 6e0c38e3bb..e6f198bff0 100644
--- a/src/bias/Bias.cpp
+++ b/src/bias/Bias.cpp
@@ -52,6 +52,7 @@ void Bias::registerKeywords( Keywords& keys ) {
   ActionPilot::registerKeywords(keys);
   ActionWithValue::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the scalars on which the bias will act");
   keys.add("hidden","STRIDE","the frequency with which the forces due to the bias should be calculated.  This can be used to correctly set up multistep algorithms");
   keys.addOutputComponent("bias","default","scalar","the instantaneous value of the bias potential");
 }
diff --git a/src/bias/BiasValue.cpp b/src/bias/BiasValue.cpp
index 928803eb31..c4272f7d17 100644
--- a/src/bias/BiasValue.cpp
+++ b/src/bias/BiasValue.cpp
@@ -83,7 +83,7 @@ PLUMED_REGISTER_ACTION(BiasValue,"BIASVALUE")
 
 void BiasValue::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("compulsory","ARG","scalar/vector","the labels of the scalar/vector arguments whose values will be used as a bias on the system");
   // Should be _bias below
   keys.addOutputComponent("_bias","default","scalar","one or multiple instances of this quantity can be referenced elsewhere in the input file. "
                           "these quantities will named with  the arguments of the bias followed by "
diff --git a/src/bias/ExtendedLagrangian.cpp b/src/bias/ExtendedLagrangian.cpp
index 8a5aff4b1d..ba66be13ea 100644
--- a/src/bias/ExtendedLagrangian.cpp
+++ b/src/bias/ExtendedLagrangian.cpp
@@ -129,7 +129,6 @@ PLUMED_REGISTER_ACTION(ExtendedLagrangian,"EXTENDED_LAGRANGIAN")
 
 void ExtendedLagrangian::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","KAPPA","specifies that the restraint is harmonic and what the values of the force constants on each of the variables are");
   keys.add("compulsory","TAU","specifies that the restraint is harmonic and what the values of the force constants on each of the variables are");
   keys.add("compulsory","FRICTION","0.0","add a friction to the variable");
diff --git a/src/bias/External.cpp b/src/bias/External.cpp
index ce422c1682..5d01ea5184 100644
--- a/src/bias/External.cpp
+++ b/src/bias/External.cpp
@@ -122,7 +122,6 @@ PLUMED_REGISTER_ACTION(External,"EXTERNAL")
 
 void External::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","FILE","the name of the file containing the external potential.");
   keys.addFlag("NOSPLINE",false,"specifies that no spline interpolation is to be used when calculating the energy and forces due to the external potential");
   keys.addFlag("SPARSE",false,"specifies that the external potential uses a sparse grid");
diff --git a/src/bias/LWalls.cpp b/src/bias/LWalls.cpp
index cfeb3f8384..ac933883ed 100644
--- a/src/bias/LWalls.cpp
+++ b/src/bias/LWalls.cpp
@@ -87,7 +87,7 @@ PLUMED_REGISTER_ACTION(LWalls,"LOWER_WALLS_SCALAR")
 
 void LWalls::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys); keys.setDisplayName("LOWER_WALLS");
-  keys.use("ARG"); keys.add("hidden","NO_ACTION_LOG","suppresses printing from action on the log");
+  keys.add("hidden","NO_ACTION_LOG","suppresses printing from action on the log");
   keys.add("compulsory","AT","the positions of the wall. The a_i in the expression for a wall.");
   keys.add("compulsory","KAPPA","the force constant for the wall.  The k_i in the expression for a wall.");
   keys.add("compulsory","OFFSET","0.0","the offset for the start of the wall.  The o_i in the expression for a wall.");
diff --git a/src/bias/MaxEnt.cpp b/src/bias/MaxEnt.cpp
index be999919cd..74dfff9f2f 100644
--- a/src/bias/MaxEnt.cpp
+++ b/src/bias/MaxEnt.cpp
@@ -163,7 +163,6 @@ PLUMED_REGISTER_ACTION(MaxEnt,"MAXENT")
 
 void MaxEnt::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","KAPPA","0.0","specifies the initial value for the learning rate");
   keys.add("compulsory","TAU","Specify the dumping time for the learning rate.");
   keys.add("compulsory","TYPE","specify the restraint type. "
diff --git a/src/bias/MetaD.cpp b/src/bias/MetaD.cpp
index 3d45b71cd8..fc0325c8c8 100644
--- a/src/bias/MetaD.cpp
+++ b/src/bias/MetaD.cpp
@@ -530,7 +530,6 @@ void MetaD::registerKeywords(Keywords& keys) {
   keys.addOutputComponent("pace","FREQUENCY_ADAPTIVE","scalar","the hill addition frequency when employing frequency adaptive metadynamics");
   keys.addOutputComponent("nlker","NLIST","scalar","number of hills in the neighbor list");
   keys.addOutputComponent("nlsteps","NLIST","scalar","number of steps from last neighbor list update");
-  keys.use("ARG");
   keys.add("compulsory","SIGMA","the widths of the Gaussian hills");
   keys.add("compulsory","PACE","the frequency for hill addition");
   keys.add("compulsory","FILE","HILLS","a file in which the list of added hills is stored");
diff --git a/src/bias/MovingRestraint.cpp b/src/bias/MovingRestraint.cpp
index bfbf9ce221..fae1def8e6 100644
--- a/src/bias/MovingRestraint.cpp
+++ b/src/bias/MovingRestraint.cpp
@@ -124,7 +124,6 @@ PLUMED_REGISTER_ACTION(MovingRestraint,"MOVINGRESTRAINT")
 
 void MovingRestraint::registerKeywords( Keywords& keys ) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","VERSE","B","Tells plumed whether the restraint is only acting for CV larger (U) or smaller (L) than "
            "the restraint or whether it is acting on both sides (B)");
   keys.add("numbered","STEP","This keyword appears multiple times as STEPx with x=0,1,2,...,n. Each value given represents "
diff --git a/src/bias/PBMetaD.cpp b/src/bias/PBMetaD.cpp
index 3f7c4b1b8d..7a4661c171 100644
--- a/src/bias/PBMetaD.cpp
+++ b/src/bias/PBMetaD.cpp
@@ -330,7 +330,6 @@ PLUMED_REGISTER_ACTION(PBMetaD,"PBMETAD")
 
 void PBMetaD::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","SIGMA","the widths of the Gaussian hills");
   keys.add("compulsory","PACE","the frequency for hill addition, one for all biases");
   keys.add("optional","FILE","files in which the lists of added hills are stored, default names are assigned using arguments if FILE is not found");
@@ -351,7 +350,7 @@ void PBMetaD::registerKeywords(Keywords& keys) {
   keys.add("optional","ADAPTIVE","use a geometric (=GEOM) or diffusion (=DIFF) based hills width scheme. Sigma is one number that has distance units or timestep dimensions");
   keys.add("optional","SIGMA_MAX","the upper bounds for the sigmas (in CV units) when using adaptive hills. Negative number means no bounds ");
   keys.add("optional","SIGMA_MIN","the lower bounds for the sigmas (in CV units) when using adaptive hills. Negative number means no bounds ");
-  keys.add("numbered","PF", "specify which CVs belong in a partitioned family. Once a PF is specified, all CVs in ARG must be placed in a PF even if there is one CV per PF”");
+  keys.addInputKeyword("numbered","PF", "scalar", "specify which CVs belong in a partitioned family. Once a PF is specified, all CVs in ARG must be placed in a PF even if there is one CV per PF”");
   keys.add("optional","SELECTOR", "add forces and do update based on the value of SELECTOR");
   keys.add("optional","SELECTOR_ID", "value of SELECTOR");
   keys.add("optional","WALKERS_ID", "walker id");
diff --git a/src/bias/Restraint.cpp b/src/bias/Restraint.cpp
index fb0f9a6b9b..f097d5f899 100644
--- a/src/bias/Restraint.cpp
+++ b/src/bias/Restraint.cpp
@@ -79,8 +79,7 @@ class Restraint : public Bias {
 PLUMED_REGISTER_ACTION(Restraint,"RESTRAINT_SCALAR")
 
 void Restraint::registerKeywords(Keywords& keys) {
-  Bias::registerKeywords(keys);
-  keys.use("ARG"); keys.setDisplayName("RESTRAINT");
+  Bias::registerKeywords(keys); keys.setDisplayName("RESTRAINT");
   keys.add("compulsory","SLOPE","0.0","specifies that the restraint is linear and what the values of the force constants on each of the variables are");
   keys.add("compulsory","KAPPA","0.0","specifies that the restraint is harmonic and what the values of the force constants on each of the variables are");
   keys.add("compulsory","AT","the position of the restraint");
diff --git a/src/bias/RestraintShortcut.cpp b/src/bias/RestraintShortcut.cpp
index 24ff3247bf..ac0d17668c 100644
--- a/src/bias/RestraintShortcut.cpp
+++ b/src/bias/RestraintShortcut.cpp
@@ -38,7 +38,7 @@ PLUMED_REGISTER_ACTION(RestraintShortcut,"RESTRAINT")
 
 void RestraintShortcut::registerKeywords(Keywords& keys) {
   ActionShortcut::registerKeywords( keys );
-  keys.add("numbered","ARG","the arguments on which the bias is acting");
+  keys.addInputKeyword("numbered","ARG","scalar/vector","the values the harmonic restraint acts upon");
   keys.add("compulsory","SLOPE","0.0","specifies that the restraint is linear and what the values of the force constants on each of the variables are");
   keys.add("compulsory","KAPPA","0.0","specifies that the restraint is harmonic and what the values of the force constants on each of the variables are");
   keys.add("compulsory","AT","the position of the restraint");
diff --git a/src/bias/ReweightBias.cpp b/src/bias/ReweightBias.cpp
index 96a9da14ec..85cc51a6f1 100644
--- a/src/bias/ReweightBias.cpp
+++ b/src/bias/ReweightBias.cpp
@@ -78,8 +78,8 @@ class ReweightBias : public ReweightBase {
 PLUMED_REGISTER_ACTION(ReweightBias,"REWEIGHT_BIAS")
 
 void ReweightBias::registerKeywords(Keywords& keys ) {
-  ReweightBase::registerKeywords( keys ); keys.remove("ARG");
-  keys.add("compulsory","ARG","*.bias","the biases that must be taken into account when reweighting");
+  ReweightBase::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","scalar","*.bias","the biases that must be taken into account when reweighting");
   keys.setValueDescription("scalar","the weight to use for this frame to negate the effect the bias");
 }
 
diff --git a/src/bias/ReweightMetad.cpp b/src/bias/ReweightMetad.cpp
index 7438540b78..886d44a2ba 100644
--- a/src/bias/ReweightMetad.cpp
+++ b/src/bias/ReweightMetad.cpp
@@ -75,8 +75,8 @@ class ReweightMetad : public ReweightBase {
 PLUMED_REGISTER_ACTION(ReweightMetad,"REWEIGHT_METAD")
 
 void ReweightMetad::registerKeywords(Keywords& keys ) {
-  ReweightBase::registerKeywords( keys ); keys.remove("ARG");
-  keys.add("compulsory","ARG","*.rbias","the biases that must be taken into account when reweighting");
+  ReweightBase::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","scalar","*.rbias","the biases that must be taken into account when reweighting");
   keys.setValueDescription("scalar","the weight to use for this frame to negate the effect the metadynamics bias");
 }
 
diff --git a/src/bias/ReweightTemperaturePressure.cpp b/src/bias/ReweightTemperaturePressure.cpp
index 7931485799..3699e3fd4c 100644
--- a/src/bias/ReweightTemperaturePressure.cpp
+++ b/src/bias/ReweightTemperaturePressure.cpp
@@ -189,9 +189,8 @@ PLUMED_REGISTER_ACTION(ReweightTemperaturePressure,"REWEIGHT_TEMP_PRESS")
 
 void ReweightTemperaturePressure::registerKeywords(Keywords& keys ) {
   ReweightBase::registerKeywords( keys );
-  keys.remove("ARG");
-  keys.add("optional","ENERGY","Energy");
-  keys.add("optional","VOLUME","Volume");
+  keys.addInputKeyword("optional","ENERGY","scalar","Energy");
+  keys.addInputKeyword("optional","VOLUME","scalar","Volume");
   keys.add("optional","REWEIGHT_PRESSURE","Reweighting pressure");
   keys.add("optional","PRESSURE","The system pressure");
   keys.add("optional","REWEIGHT_TEMP","Reweighting temperature");
diff --git a/src/bias/UWalls.cpp b/src/bias/UWalls.cpp
index 15bdda72e2..635aca09c8 100644
--- a/src/bias/UWalls.cpp
+++ b/src/bias/UWalls.cpp
@@ -86,7 +86,7 @@ PLUMED_REGISTER_ACTION(UWalls,"UPPER_WALLS_SCALAR")
 
 void UWalls::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys); keys.setDisplayName("UPPER_WALLS");
-  keys.use("ARG"); keys.add("hidden","NO_ACTION_LOG","suppresses printing from action on the log");
+  keys.add("hidden","NO_ACTION_LOG","suppresses printing from action on the log");
   keys.add("compulsory","AT","the positions of the wall. The a_i in the expression for a wall.");
   keys.add("compulsory","KAPPA","the force constant for the wall.  The k_i in the expression for a wall.");
   keys.add("compulsory","OFFSET","0.0","the offset for the start of the wall.  The o_i in the expression for a wall.");
diff --git a/src/bias/Walls.cpp b/src/bias/Walls.cpp
index 668e8588fb..28d5c89e04 100644
--- a/src/bias/Walls.cpp
+++ b/src/bias/Walls.cpp
@@ -39,7 +39,7 @@ PLUMED_REGISTER_ACTION(Walls,"LOWER_WALLS")
 
 void Walls::registerKeywords(Keywords& keys) {
   ActionShortcut::registerKeywords(keys);
-  keys.add("numbered","ARG","the arguments on which the bias is acting");
+  keys.addInputKeyword("numbered","ARG","scalar/vector","the arguments on which the bias is acting");
   keys.add("compulsory","AT","the positions of the wall. The a_i in the expression for a wall.");
   keys.add("compulsory","KAPPA","the force constant for the wall.  The k_i in the expression for a wall.");
   keys.add("compulsory","OFFSET","0.0","the offset for the start of the wall.  The o_i in the expression for a wall.");
diff --git a/src/cltools/GenJson.cpp b/src/cltools/GenJson.cpp
index 57d8873848..a7d599bab1 100644
--- a/src/cltools/GenJson.cpp
+++ b/src/cltools/GenJson.cpp
@@ -121,7 +121,9 @@ int GenJson::main(FILE* in, FILE*out,Communicator& pc) {
       }
       std::size_t dot=desc.find_first_of("."); std::string mydescrip = desc.substr(0,dot);
       if( mydescrip.find("\\")!=std::string::npos ) error("found invalid backslash character documentation for keyword " + keys.getKeyword(j) + " in action " + action_names[i] );
-      std::cout<<"       \""<<keys.getKeyword(j)<<"\" : { \"type\": \""<<keys.getStyle(keys.getKeyword(j))<<"\", \"description\": \""<<mydescrip<<"\", \"multiple\": "<<keys.numbered( keys.getKeyword(j) )<<"}";
+      std::string argtype = keys.getArgumentType( keys.getKeyword(j) );
+      if( argtype.length()>0 ) std::cout<<"       \""<<keys.getKeyword(j)<<"\" : { \"type\": \""<<keys.getStyle(keys.getKeyword(j))<<"\", \"description\": \""<<mydescrip<<"\", \"multiple\": "<<keys.numbered( keys.getKeyword(j) )<<", \"argtype\": \""<<argtype<<"\"}";
+      else std::cout<<"       \""<<keys.getKeyword(j)<<"\" : { \"type\": \""<<keys.getStyle(keys.getKeyword(j))<<"\", \"description\": \""<<mydescrip<<"\", \"multiple\": "<<keys.numbered( keys.getKeyword(j) )<<"}";
       if( j==keys.size()-1 && !keys.exists("HAS_VALUES") ) std::cout<<std::endl; else std::cout<<","<<std::endl;
     }
     if( keys.exists("HAS_VALUES") ) {
diff --git a/src/clusters/ClusterDistribution.cpp b/src/clusters/ClusterDistribution.cpp
index fe0d67dca3..16fd0b1944 100644
--- a/src/clusters/ClusterDistribution.cpp
+++ b/src/clusters/ClusterDistribution.cpp
@@ -99,8 +99,8 @@ void ClusterDistribution::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys );
   ActionWithArguments::registerKeywords( keys );
   ActionWithValue::registerKeywords( keys ); keys.remove("NUMERICAL_DERIVATIVES");
-  keys.add("compulsory","CLUSTERS","the label of the action that does the clustering"); keys.setDisplayName("CLUSTER_DISTRIBUTION");
-  keys.add("optional","WEIGHTS","use the vector of values calculated by this action as weights rather than giving each atom a unit weight");
+  keys.addInputKeyword("compulsory","CLUSTERS","vector","the label of the action that does the clustering"); keys.setDisplayName("CLUSTER_DISTRIBUTION");
+  keys.addInputKeyword("optional","WEIGHTS","vector","use the vector of values calculated by this action as weights rather than giving each atom a unit weight");
   keys.setValueDescription("vector","a vector containing the sum of a atomic-cv that is calculated for each of the identified clusters");
 }
 
diff --git a/src/clusters/ClusterWeights.cpp b/src/clusters/ClusterWeights.cpp
index fea3d249d4..36d3952699 100644
--- a/src/clusters/ClusterWeights.cpp
+++ b/src/clusters/ClusterWeights.cpp
@@ -64,9 +64,9 @@ PLUMED_REGISTER_ACTION(ClusterWeights,"CLUSTER_WEIGHTS")
 
 void ClusterWeights::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.remove("ARG");
+  ActionWithArguments::registerKeywords( keys );
   ActionWithValue::registerKeywords( keys ); keys.remove("NUMERICAL_DERIVATIVES");
-  keys.add("compulsory","CLUSTERS","the label of the action that does the clustering");
+  keys.addInputKeyword("compulsory","CLUSTERS","vector","the label of the action that does the clustering");
   keys.add("compulsory","CLUSTER","1","which cluster would you like to look at 1 is the largest cluster, 2 is the second largest, 3 is the the third largest and so on.");
   keys.addFlag("LOWMEM",false,"this flag does nothing and is present only to ensure back-compatibility");
   // keys.add("hidden","FROM_PROPERTIES","indicates that this is created from CLUSTER_PROPERTIES shortcut");
diff --git a/src/clusters/ClusteringBase.cpp b/src/clusters/ClusteringBase.cpp
index 53791e2488..6efe3c7b84 100644
--- a/src/clusters/ClusteringBase.cpp
+++ b/src/clusters/ClusteringBase.cpp
@@ -26,7 +26,7 @@ namespace PLMD {
 namespace clusters {
 
 void ClusteringBase::registerKeywords( Keywords& keys ) {
-  matrixtools::MatrixOperationBase::registerKeywords( keys ); keys.use("ARG");
+  matrixtools::MatrixOperationBase::registerKeywords( keys );
   keys.setValueDescription("vector","vector with length that is equal to the number of rows in the input matrix.  Elements of this vector are equal to the cluster that each node is a part of");
 }
 
diff --git a/src/colvar/RMSDVector.cpp b/src/colvar/RMSDVector.cpp
index 9010a3fdb4..8f00c15b57 100644
--- a/src/colvar/RMSDVector.cpp
+++ b/src/colvar/RMSDVector.cpp
@@ -40,7 +40,8 @@ namespace colvar {
 PLUMED_REGISTER_ACTION(RMSDVector,"RMSD_VECTOR")
 
 void RMSDVector::registerKeywords(Keywords& keys) {
-  ActionWithVector::registerKeywords(keys); keys.use("ARG"); keys.setDisplayName("RMSD");
+  ActionWithVector::registerKeywords(keys); keys.setDisplayName("RMSD");
+  keys.addInputKeyword("compulsory","ARG","vector/matrix","the labels of two actions that you are calculating the RMSD between");
   keys.add("compulsory","TYPE","SIMPLE","the manner in which RMSD alignment is performed.  Should be OPTIMAL or SIMPLE.");
   keys.add("compulsory","ALIGN","1.0","the weights to use when aligning to the reference structure");
   keys.add("compulsory","DISPLACE","1.0","the weights to use when calculating the displacement from the reference structure");
diff --git a/src/contour/ContourFindingBase.cpp b/src/contour/ContourFindingBase.cpp
index 85fea0fa80..5ef200e749 100644
--- a/src/contour/ContourFindingBase.cpp
+++ b/src/contour/ContourFindingBase.cpp
@@ -25,7 +25,8 @@ namespace PLMD {
 namespace contour {
 
 void ContourFindingBase::registerKeywords( Keywords& keys ) {
-  gridtools::ActionWithGrid::registerKeywords( keys ); keys.use("ARG");
+  gridtools::ActionWithGrid::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","grid","the labels of the grid in which the contour will be found");
   keys.add("compulsory","CONTOUR","the value we would like to draw the contour at in the space");
   gridtools::EvaluateGridFunction gg; gg.registerKeywords(keys);
 }
diff --git a/src/contour/DistanceFromContourBase.cpp b/src/contour/DistanceFromContourBase.cpp
index 6444830865..c65f80f209 100644
--- a/src/contour/DistanceFromContourBase.cpp
+++ b/src/contour/DistanceFromContourBase.cpp
@@ -27,7 +27,8 @@ namespace contour {
 void DistanceFromContourBase::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
   ActionAtomistic::registerKeywords( keys ); ActionWithArguments::registerKeywords( keys );
-  keys.remove("NUMERICAL_DERIVATIVES"); keys.use("ARG");
+  keys.remove("NUMERICAL_DERIVATIVES");
+  keys.addInputKeyword("optional","ARG","vector","the label of the weights to use when constructing the density.  If this keyword is not here the weights are assumed to be one.");
   keys.add("atoms","POSITIONS","the positions of the atoms that we are calculating the contour from");
   keys.add("atoms","ATOM","The atom whose perpendicular distance we are calculating from the contour");
   keys.add("compulsory","BANDWIDTH","the bandwidths for kernel density esimtation");
diff --git a/src/contour/DumpContour.cpp b/src/contour/DumpContour.cpp
index 3377f38f45..06ceec0b2b 100644
--- a/src/contour/DumpContour.cpp
+++ b/src/contour/DumpContour.cpp
@@ -57,7 +57,8 @@ PLUMED_REGISTER_ACTION(DumpContour,"DUMPCONTOUR")
 void DumpContour::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys );
   ActionPilot::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","vector","the labels of the values that should be output to the file");
   keys.add("compulsory","STRIDE","1","the frequency with which the grid should be output to the file.");
   keys.add("compulsory","FILE","density","the file on which to write the grid.");
   keys.add("optional","FMT","the format that should be used to output real numbers");
diff --git a/src/core/ActionToGetData.cpp b/src/core/ActionToGetData.cpp
index a5ca406325..e1f3fad415 100644
--- a/src/core/ActionToGetData.cpp
+++ b/src/core/ActionToGetData.cpp
@@ -38,9 +38,9 @@ PLUMED_REGISTER_ACTION(ActionToGetData,"GET")
 
 void ActionToGetData::registerKeywords(Keywords& keys) {
   Action::registerKeywords(keys); ActionPilot::registerKeywords(keys); ActionWithArguments::registerKeywords(keys);
+  keys.addInputKeyword("optional","ARG","scalar/vector/matrix/grid","the label of the value that you would like to GET");
   keys.add("compulsory","STRIDE","1","the frequency with which the quantities of interest should be stored");
   keys.add("compulsory","TYPE","value","what do you want to collect for the value can be derivative/force");
-  keys.use("ARG");
   keys.setValueDescription("scalar/vector/matrix/grid","a copy of the data in the value specified by the ARG keyword");
 }
 
diff --git a/src/core/ActionWithArguments.cpp b/src/core/ActionWithArguments.cpp
index a1b9208e6a..71f2f1c019 100644
--- a/src/core/ActionWithArguments.cpp
+++ b/src/core/ActionWithArguments.cpp
@@ -35,19 +35,20 @@
 namespace PLMD {
 
 void ActionWithArguments::registerKeywords(Keywords& keys) {
-  keys.reserve("numbered","ARG","the input for this action is the scalar output from one or more other actions. The particular scalars that you will use "
-               "are referenced using the label of the action. If the label appears on its own then it is assumed that the Action calculates "
-               "a single scalar value.  The value of this scalar is thus used as the input to this new action.  If * or *.* appears the "
-               "scalars calculated by all the proceeding actions in the input file are taken.  Some actions have multi-component outputs and "
-               "each component of the output has a specific label.  For example a \\ref DISTANCE action labelled dist may have three components "
-               "x, y and z.  To take just the x component you should use dist.x, if you wish to take all three components then use dist.*."
-               "More information on the referencing of Actions can be found in the section of the manual on the PLUMED \\ref Syntax.  "
-               "Scalar values can also be "
-               "referenced using POSIX regular expressions as detailed in the section on \\ref Regex. To use this feature you you must compile "
-               "PLUMED with the appropriate flag.");
+//  keys.reserve("numbered","ARG","the input for this action is the scalar output from one or more other actions. The particular scalars that you will use "
+//               "are referenced using the label of the action. If the label appears on its own then it is assumed that the Action calculates "
+//               "a single scalar value.  The value of this scalar is thus used as the input to this new action.  If * or *.* appears the "
+//               "scalars calculated by all the proceeding actions in the input file are taken.  Some actions have multi-component outputs and "
+//               "each component of the output has a specific label.  For example a \\ref DISTANCE action labelled dist may have three components "
+//               "x, y and z.  To take just the x component you should use dist.x, if you wish to take all three components then use dist.*."
+//               "More information on the referencing of Actions can be found in the section of the manual on the PLUMED \\ref Syntax.  "
+//               "Scalar values can also be "
+//               "referenced using POSIX regular expressions as detailed in the section on \\ref Regex. To use this feature you you must compile "
+//               "PLUMED with the appropriate flag.");
 }
 
 void ActionWithArguments::parseArgumentList(const std::string&key,std::vector<Value*>&arg) {
+  if( keywords.getArgumentType(key).length()==0 ) warning("keyword " + key + " for reading arguments should is registered using Keyword::add rather than Keyword::addInputKeyword.  The keyword will thus not appear in the correct place in the manual");
   std::string def; std::vector<std::string> c; arg.clear(); parseVector(key,c);
   if( c.size()==0 && (keywords.style(key,"compulsory") || keywords.style(key,"hidden")) ) {
     if( keywords.getDefaultValue(key,def) ) c.push_back( def );
@@ -57,6 +58,7 @@ void ActionWithArguments::parseArgumentList(const std::string&key,std::vector<Va
 }
 
 bool ActionWithArguments::parseArgumentList(const std::string&key,int i,std::vector<Value*>&arg) {
+  if( keywords.getArgumentType(key).length()==0 ) warning("keyword " + key + " for reading argument should is registered using Keyword::add rather than Keyword::addInputKeyword.  The keyword will thus not appear in the correct place in the manual");
   std::vector<std::string> c;
   arg.clear();
   if(parseNumberedVector(key,i,c)) {
@@ -189,6 +191,9 @@ void ActionWithArguments::interpretArgumentList(const std::vector<std::string>&
       }
     }
   }
+  for(unsigned i=0; i<arg.size(); ++i) {
+    if( !readact->keywords.checkArgumentType( arg[i]->getRank(), arg[i]->hasDerivatives() ) ) readact->warning("documentation for input type is not provided in " + readact->getName() );
+  }
 }
 
 void ActionWithArguments::expandArgKeywordInPDB( const PDB& pdb ) {
diff --git a/src/core/ActionWithMatrix.cpp b/src/core/ActionWithMatrix.cpp
index bc0609f41b..2ddadb5384 100644
--- a/src/core/ActionWithMatrix.cpp
+++ b/src/core/ActionWithMatrix.cpp
@@ -25,7 +25,7 @@
 namespace PLMD {
 
 void ActionWithMatrix::registerKeywords( Keywords& keys ) {
-  ActionWithVector::registerKeywords( keys ); keys.use("ARG");
+  ActionWithVector::registerKeywords( keys );
 }
 
 ActionWithMatrix::ActionWithMatrix(const ActionOptions&ao):
diff --git a/src/crystdistrib/QuaternionBondProductMatrix.cpp b/src/crystdistrib/QuaternionBondProductMatrix.cpp
index 0fea48baae..ce14058cc2 100644
--- a/src/crystdistrib/QuaternionBondProductMatrix.cpp
+++ b/src/crystdistrib/QuaternionBondProductMatrix.cpp
@@ -73,7 +73,8 @@ PLUMED_REGISTER_ACTION(QuaternionBondProductMatrix,"QUATERNION_BOND_PRODUCT_MATR
 
 
 void QuaternionBondProductMatrix::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords(keys); keys.use("ARG");
+  ActionWithMatrix::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","vector/matrix","this action takes 8 arguments.  The first four should be the w,i,j and k components of a quaternion vector.  The second four should be contact matrix and the matrices should be the x, y and z components of the bond vectors");
   keys.addOutputComponent("w","default","matrix","the real component of quaternion");
   keys.addOutputComponent("i","default","matrix","the i component of the quaternion");
   keys.addOutputComponent("j","default","matrix","the j component of the quaternion");
diff --git a/src/crystdistrib/QuaternionProductMatrix.cpp b/src/crystdistrib/QuaternionProductMatrix.cpp
index 0210f87810..a14cca09c4 100644
--- a/src/crystdistrib/QuaternionProductMatrix.cpp
+++ b/src/crystdistrib/QuaternionProductMatrix.cpp
@@ -50,7 +50,8 @@ class QuaternionProductMatrix : public ActionWithMatrix {
 PLUMED_REGISTER_ACTION(QuaternionProductMatrix,"QUATERNION_PRODUCT_MATRIX")
 
 void QuaternionProductMatrix::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords(keys); keys.use("ARG");
+  ActionWithMatrix::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","vector","the labels of the quaternion vectors that you are outer product of");
   keys.addOutputComponent("w","default","matrix","the real component of quaternion");
   keys.addOutputComponent("i","default","matrix","the i component of the quaternion");
   keys.addOutputComponent("j","default","matrix","the j component of the quaternion");
diff --git a/src/dimred/ArrangePoints.cpp b/src/dimred/ArrangePoints.cpp
index 19d1f265a0..5296042c94 100644
--- a/src/dimred/ArrangePoints.cpp
+++ b/src/dimred/ArrangePoints.cpp
@@ -70,10 +70,11 @@ PLUMED_REGISTER_ACTION(ArrangePoints,"ARRANGE_POINTS")
 
 void ArrangePoints::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
-  keys.add("numbered","TARGET","the matrix of target quantities that you would like to match");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","vector","the initial positions for the projections");
+  keys.addInputKeyword("numbered","TARGET","matrix","the matrix of target quantities that you would like to match");
   keys.add("numbered","FUNC","a function that is applied on the distances between the points in the low dimensional space");
-  keys.add("numbered","WEIGHTS","the matrix with the weights of the target quantities");
+  keys.addInputKeyword("numbered","WEIGHTS","matrix","the matrix with the weights of the target quantities");
   keys.add("compulsory","MINTYPE","conjgrad","the method to use for the minimisation");
   keys.add("compulsory","MAXITER","1000","maximum number of optimization cycles for optimisation algorithms");
   keys.add("compulsory","CGTOL","1E-6","the tolerance for the conjugate gradient minimization");
diff --git a/src/dimred/ProjectPoints.cpp b/src/dimred/ProjectPoints.cpp
index f200e12247..128eeadf31 100644
--- a/src/dimred/ProjectPoints.cpp
+++ b/src/dimred/ProjectPoints.cpp
@@ -60,10 +60,11 @@ class ProjectPoints : public ActionWithVector {
 PLUMED_REGISTER_ACTION(ProjectPoints,"PROJECT_POINTS")
 
 void ProjectPoints::registerKeywords( Keywords& keys ) {
-  ActionWithVector::registerKeywords( keys ); keys.use("ARG");
-  keys.add("numbered","TARGET","the matrix of target quantities that you would like to match");
+  ActionWithVector::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","vector","the projections of the landmark points");
+  keys.addInputKeyword("numbered","TARGET","vector/matrix","the matrix of target quantities that you would like to match");
   keys.add("numbered","FUNC","a function that is applied on the distances between the points in the low dimensional space");
-  keys.add("numbered","WEIGHTS","the matrix with the weights of the target quantities");
+  keys.addInputKeyword("numbered","WEIGHTS","vector","the matrix with the weights of the target quantities");
   keys.add("compulsory","CGTOL","1E-6","the tolerance for the conjugate gradient minimization");
   keys.addOutputComponent("coord","default","scalar/vector","the coordinates of the points in the low dimensional space");
 }
diff --git a/src/drr/DynamicReferenceRestraining.cpp b/src/drr/DynamicReferenceRestraining.cpp
index 77c40ff532..c85ece3ece 100644
--- a/src/drr/DynamicReferenceRestraining.cpp
+++ b/src/drr/DynamicReferenceRestraining.cpp
@@ -246,7 +246,6 @@ PLUMED_REGISTER_ACTION(DynamicReferenceRestraining, "DRR")
 
 void DynamicReferenceRestraining::registerKeywords(Keywords &keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("optional", "KAPPA", "specifies that the restraint is harmonic and "
            "what the values of the force constants on "
            "each of the variables are (default to "
diff --git a/src/eds/EDS.cpp b/src/eds/EDS.cpp
index f2be25e4d0..8444f48cbf 100644
--- a/src/eds/EDS.cpp
+++ b/src/eds/EDS.cpp
@@ -281,10 +281,9 @@ PLUMED_REGISTER_ACTION(EDS, "EDS")
 void EDS::registerKeywords(Keywords &keys)
 {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("optional", "CENTER", "The desired centers (equilibrium values) which will be sought during the adaptive linear biasing. This is for fixed centers");
-  keys.add("optional", "CENTER_ARG", "The desired centers (equilibrium values) which will be sought during the adaptive linear biasing. "
-           "CENTER_ARG is for calculated centers, e.g. from a CV or analysis. ");
+  keys.addInputKeyword("optional", "CENTER_ARG", "scalar", "The desired centers (equilibrium values) which will be sought during the adaptive linear biasing. "
+                       "CENTER_ARG is for calculated centers, e.g. from a CV or analysis. ");
 
   keys.add("optional", "PERIOD", "Steps over which to adjust bias for adaptive or ramping");
   keys.add("compulsory", "RANGE", "25.0", "The (starting) maximum increase in coupling constant per PERIOD (in k_B T/[BIAS_SCALE unit]) for each CV biased");
@@ -298,7 +297,7 @@ void EDS::registerKeywords(Keywords &keys)
            "Must be in interval [1,0), where 1 indicates all and any other indicates a stochastic update. "
            "If not set, default is 1 / N, where N is the number of CVs. ");
   keys.add("optional", "VIRIAL", "Add an update penalty for having non-zero virial contributions. Only makes sense with multiple correlated CVs.");
-  keys.add("optional", "LOGWEIGHTS", "Add weights to use for computing statistics. For example, if biasing with metadynamics.");
+  keys.addInputKeyword("optional", "LOGWEIGHTS", "scalar", "Add weights to use for computing statistics. For example, if biasing with metadynamics.");
   keys.addFlag("LM", false, "Use Levenberg-Marquadt algorithm along with simultaneous keyword. Otherwise use gradient descent.");
   keys.add("compulsory", "LM_MIXING", "1", "Initial mixing parameter when using Levenberg-Marquadt minimization.");
   keys.add("optional", "RESTART_FMT", "the format that should be used to output real numbers in EDS restarts");
diff --git a/src/fisst/FISST.cpp b/src/fisst/FISST.cpp
index 4e65c461ee..2db59fb765 100644
--- a/src/fisst/FISST.cpp
+++ b/src/fisst/FISST.cpp
@@ -166,7 +166,6 @@ PLUMED_REGISTER_ACTION(FISST,"FISST")
 
 void FISST::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","PERIOD","Steps corresponding to the learning rate");
   keys.add("optional","RESET_PERIOD","Reset the learning statistics every time this number of steps comes around.");
   keys.add("compulsory","NINTERPOLATE","Number of grid points on which to do interpolation.");
diff --git a/src/fourier/FourierTransform.cpp b/src/fourier/FourierTransform.cpp
index a66cf6091b..1207f2f3fd 100644
--- a/src/fourier/FourierTransform.cpp
+++ b/src/fourier/FourierTransform.cpp
@@ -87,7 +87,8 @@ class FourierTransform : public gridtools::ActionWithGrid {
 PLUMED_REGISTER_ACTION(FourierTransform,"FOURIER_TRANSFORM")
 
 void FourierTransform::registerKeywords( Keywords& keys ) {
-  ActionWithGrid::registerKeywords( keys ); keys.use("ARG");
+  ActionWithGrid::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","grid","the label of the grid that you want to fourer transform");
   keys.add("optional","FT_TYPE","choose what kind of data you want as output on the grid. Possible values are: ABS = compute the complex modulus of Fourier coefficients (DEFAULT); NORM = compute the norm (i.e. ABS^2) of Fourier coefficients; COMPLEX = store the FFTW complex output on the grid (as a vector).");
   keys.add("compulsory","FOURIER_PARAMETERS","default","what kind of normalization is applied to the output and if the Fourier transform in FORWARD or BACKWARD. This keyword takes the form FOURIER_PARAMETERS=A,B, where A and B can be 0, 1 or -1. The default values are A=1 (no normalization at all) and B=1 (forward FFT). Other possible choices for A are: "
            "A=-1: normalize by the number of data, "
diff --git a/src/function/Ensemble.cpp b/src/function/Ensemble.cpp
index 137dc77ab8..1121f9d976 100644
--- a/src/function/Ensemble.cpp
+++ b/src/function/Ensemble.cpp
@@ -73,7 +73,6 @@ PLUMED_REGISTER_ACTION(Ensemble,"ENSEMBLE")
 
 void Ensemble::registerKeywords(Keywords& keys) {
   Function::registerKeywords(keys);
-  keys.use("ARG");
   keys.addFlag("REWEIGHT",false,"simple REWEIGHT using the latest ARG as energy");
   keys.addFlag("CENTRAL",false,"calculate a central moment instead of a standard moment");
   keys.add("optional","TEMP","the system temperature - this is only needed if you are reweighting");
diff --git a/src/function/FuncPathGeneral.cpp b/src/function/FuncPathGeneral.cpp
index be30f5bed4..4dd0ada991 100644
--- a/src/function/FuncPathGeneral.cpp
+++ b/src/function/FuncPathGeneral.cpp
@@ -155,7 +155,6 @@ void FuncPathGeneral::loadReference() {
 
 void FuncPathGeneral::registerKeywords(Keywords& keys) {
   Function::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory", "LAMBDA", "Lambda parameter required for smoothing");
   keys.add("compulsory", "COEFFICIENTS", "Coefficients to be assigned to the CVs");
   keys.add("compulsory", "REFERENCE", "Colvar file needed to provide the CV milestones");
diff --git a/src/function/FuncPathMSD.cpp b/src/function/FuncPathMSD.cpp
index 1905ceb412..5070c284f9 100644
--- a/src/function/FuncPathMSD.cpp
+++ b/src/function/FuncPathMSD.cpp
@@ -219,7 +219,6 @@ PLUMED_REGISTER_ACTION(FuncPathMSD,"FUNCPATHMSD")
 
 void FuncPathMSD::registerKeywords(Keywords& keys) {
   Function::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","LAMBDA","the lambda parameter is needed for smoothing, is in the units of plumed");
   keys.add("optional","NEIGH_SIZE","size of the neighbor list");
   keys.add("optional","NEIGH_STRIDE","how often the neighbor list needs to be calculated in time units");
diff --git a/src/function/FuncSumHills.cpp b/src/function/FuncSumHills.cpp
index f3ce2fbbee..627063b717 100644
--- a/src/function/FuncSumHills.cpp
+++ b/src/function/FuncSumHills.cpp
@@ -200,7 +200,6 @@ PLUMED_REGISTER_ACTION(FuncSumHills,"FUNCSUMHILLS")
 
 void FuncSumHills::registerKeywords(Keywords& keys) {
   Function::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("optional","HILLSFILES"," source file for hills creation(may be the same as HILLS)"); // this can be a vector!
   keys.add("optional","HISTOFILES"," source file for histogram creation(may be the same as HILLS)"); // also this can be a vector!
   keys.add("optional","HISTOSIGMA"," sigmas for binning when the histogram correction is needed    ");
diff --git a/src/function/Function.cpp b/src/function/Function.cpp
index 053c4a9943..8ca01b585d 100644
--- a/src/function/Function.cpp
+++ b/src/function/Function.cpp
@@ -30,6 +30,7 @@ void Function::registerKeywords(Keywords& keys) {
   Action::registerKeywords(keys);
   ActionWithValue::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the values from which the function is calculated");
   keys.reserve("compulsory","PERIODIC","if the output of your function is periodic then you should specify the periodicity of the function.  If the output is not periodic you must state this using PERIODIC=NO");
 }
 
diff --git a/src/function/FunctionOfMatrix.h b/src/function/FunctionOfMatrix.h
index dd56dcbdec..048942acc1 100644
--- a/src/function/FunctionOfMatrix.h
+++ b/src/function/FunctionOfMatrix.h
@@ -75,8 +75,9 @@ class FunctionOfMatrix : public ActionWithMatrix {
 
 template <class T>
 void FunctionOfMatrix<T>::registerKeywords(Keywords& keys ) {
-  ActionWithMatrix::registerKeywords(keys); keys.use("ARG"); std::string name = keys.getDisplayName();
+  ActionWithMatrix::registerKeywords(keys); std::string name = keys.getDisplayName();
   std::size_t und=name.find("_MATRIX"); keys.setDisplayName( name.substr(0,und) );
+  keys.addInputKeyword("compulsory","ARG","scalar/matrix","the labels of the scalar and matrices that on which the function is being calculated elementwise");
   keys.add("hidden","NO_ACTION_LOG","suppresses printing from action on the log");
   keys.reserve("compulsory","PERIODIC","if the output of your function is periodic then you should specify the periodicity of the function.  If the output is not periodic you must state this using PERIODIC=NO");
   T tfunc; tfunc.registerKeywords( keys );
diff --git a/src/function/FunctionOfScalar.h b/src/function/FunctionOfScalar.h
index 897fce271f..b9bef49d02 100644
--- a/src/function/FunctionOfScalar.h
+++ b/src/function/FunctionOfScalar.h
@@ -54,12 +54,13 @@ class FunctionOfScalar : public Function {
 
 template <class T>
 void FunctionOfScalar<T>::registerKeywords(Keywords& keys) {
-  Function::registerKeywords(keys); keys.use("ARG"); std::string name = keys.getDisplayName();
+  Function::registerKeywords(keys); std::string name = keys.getDisplayName();
   std::size_t und=name.find("_SCALAR"); keys.setDisplayName( name.substr(0,und) );
   keys.add("hidden","NO_ACTION_LOG","suppresses printing from action on the log");
   T tfunc; tfunc.registerKeywords( keys );
   if( keys.getDisplayName()=="SUM" ) keys.setValueDescription("scalar","the sum of all the input arguments");
   else if( keys.getDisplayName()=="MEAN" ) keys.setValueDescription("scalar","the mean of all the input arguments");
+  else if( keys.getDisplayName()=="EVALUATE_FUNCTION_FROM_GRID" ) keys.addInputKeyword("compulsory","ARG","scalar/grid","");
 }
 
 template <class T>
diff --git a/src/function/FunctionOfVector.h b/src/function/FunctionOfVector.h
index 9460f10258..dafebfed4a 100644
--- a/src/function/FunctionOfVector.h
+++ b/src/function/FunctionOfVector.h
@@ -74,8 +74,9 @@ class FunctionOfVector : public ActionWithVector {
 
 template <class T>
 void FunctionOfVector<T>::registerKeywords(Keywords& keys ) {
-  Action::registerKeywords(keys); ActionWithValue::registerKeywords(keys); ActionWithArguments::registerKeywords(keys); keys.use("ARG");
+  Action::registerKeywords(keys); ActionWithValue::registerKeywords(keys); ActionWithArguments::registerKeywords(keys);
   std::string name = keys.getDisplayName(); std::size_t und=name.find("_VECTOR"); keys.setDisplayName( name.substr(0,und) );
+  keys.addInputKeyword("compulsory","ARG","scalar/vector","the labels of the scalar and vector that on which the function is being calculated elementwise");
   keys.reserve("compulsory","PERIODIC","if the output of your function is periodic then you should specify the periodicity of the function.  If the output is not periodic you must state this using PERIODIC=NO");
   keys.add("hidden","NO_ACTION_LOG","suppresses printing from action on the log");
   T tfunc; tfunc.registerKeywords( keys );
diff --git a/src/function/FunctionShortcut.h b/src/function/FunctionShortcut.h
index 7a730dbddb..9dc006dbbf 100644
--- a/src/function/FunctionShortcut.h
+++ b/src/function/FunctionShortcut.h
@@ -46,10 +46,12 @@ class FunctionShortcut : public ActionShortcut {
 template <class T>
 void FunctionShortcut<T>::registerKeywords(Keywords& keys ) {
   ActionShortcut::registerKeywords( keys );
-  keys.add("numbered","ARG","the input to this function");
   keys.reserve("compulsory","PERIODIC","if the output of your function is periodic then you should specify the periodicity of the function.  If the output is not periodic you must state this using PERIODIC=NO");
   keys.addActionNameSuffix("_SCALAR"); keys.addActionNameSuffix("_VECTOR"); keys.addActionNameSuffix("_MATRIX"); keys.addActionNameSuffix("_GRID");
   T tfunc; tfunc.registerKeywords( keys );
+  if( keys.getDisplayName()=="SUM" || keys.getDisplayName()=="CUSTOM" || keys.getDisplayName()=="MATHEVAL" ) {
+    keys.addInputKeyword("compulsory","ARG","scalar/vector/matrix/grid","the values input to this function");
+  } else keys.addInputKeyword("compulsory","ARG","scalar/vector/matrix","the values input to this function");
 }
 
 template <class T>
diff --git a/src/function/LocalEnsemble.cpp b/src/function/LocalEnsemble.cpp
index f417f3fb8c..61a80a9794 100644
--- a/src/function/LocalEnsemble.cpp
+++ b/src/function/LocalEnsemble.cpp
@@ -90,7 +90,7 @@ PLUMED_REGISTER_ACTION(LocalEnsemble,"LOCALENSEMBLE")
 
 void LocalEnsemble::registerKeywords(Keywords& keys) {
   Function::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("numbered","ARG","scalar","the labels of the actions that you want to use");
   keys.add("compulsory","NUM","the number of local replicas");
   useCustomisableComponents(keys);
 }
diff --git a/src/function/Stats.cpp b/src/function/Stats.cpp
index d68378d965..f3876c6aac 100644
--- a/src/function/Stats.cpp
+++ b/src/function/Stats.cpp
@@ -71,8 +71,7 @@ PLUMED_REGISTER_ACTION(Stats,"STATS")
 
 void Stats::registerKeywords(Keywords& keys) {
   Function::registerKeywords(keys);
-  keys.use("ARG");
-  keys.add("optional","PARARG","the input for this action is the scalar output from one or more other actions without derivatives.");
+  keys.addInputKeyword("optional","PARARG","scalar","the input for this action is the scalar output from one or more other actions without derivatives.");
   keys.add("optional","PARAMETERS","the parameters of the arguments in your function");
   keys.addFlag("SQDEVSUM",false,"calculates only SQDEVSUM");
   keys.addFlag("SQDEV",false,"calculates and store the SQDEV as components");
diff --git a/src/funnel/Funnel.cpp b/src/funnel/Funnel.cpp
index 7a9c83b851..0f0594050c 100644
--- a/src/funnel/Funnel.cpp
+++ b/src/funnel/Funnel.cpp
@@ -144,7 +144,6 @@ PLUMED_REGISTER_ACTION(Funnel,"FUNNEL")
 
 void Funnel::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.addFlag("NOSPLINE",false,"specifies that no spline interpolation is to be used when calculating the energy and forces due to the external potential");
   keys.addFlag("SPARSE",false,"specifies that the external potential uses a sparse grid");
   keys.addFlag("SPHERE",false, "The Funnel potential including the binding site can be spherical instead of a cone");
diff --git a/src/generic/Accumulate.cpp b/src/generic/Accumulate.cpp
index 8730b7f65c..efa093db43 100644
--- a/src/generic/Accumulate.cpp
+++ b/src/generic/Accumulate.cpp
@@ -62,7 +62,8 @@ PLUMED_REGISTER_ACTION(Accumulate,"ACCUMULATE")
 void Accumulate::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
   ActionWithArguments::registerKeywords( keys ); ActionPilot::registerKeywords( keys );
-  keys.use("ARG"); keys.use("UPDATE_FROM"); keys.use("UPDATE_UNTIL");
+  keys.use("UPDATE_FROM"); keys.use("UPDATE_UNTIL");
+  keys.addInputKeyword("compulsory","ARG","scalar/grid","the label of the argument that is being added to on each timestep");
   keys.add("compulsory","STRIDE","1","the frequency with which the data should be collected and added to the quantity being averaged");
   keys.add("compulsory","CLEAR","0","the frequency with which to clear all the accumulated data.  The default value "
            "of 0 implies that all the data will be used and that the grid will never be cleared");
diff --git a/src/generic/Average.cpp b/src/generic/Average.cpp
index 7aefebc604..9fa22b7016 100644
--- a/src/generic/Average.cpp
+++ b/src/generic/Average.cpp
@@ -100,7 +100,7 @@ PLUMED_REGISTER_ACTION(Average,"AVERAGE")
 
 void Average::registerKeywords( Keywords& keys ) {
   ActionShortcut::registerKeywords( keys );
-  keys.add("compulsory","ARG","the quantity that is being averaged");
+  keys.addInputKeyword("compulsory","ARG","scalar/grid","the quantity that is being averaged");
   keys.add("optional","LOGWEIGHTS","the logarithm of the quantity to use as the weights when calculating averages");
   keys.add("compulsory","STRIDE","1","the frequency with which to store data for averaging");
   keys.add("compulsory","CLEAR","0","the frequency with whihc to clear the data that is being averaged");
diff --git a/src/generic/Collect.cpp b/src/generic/Collect.cpp
index 39660eaa08..5e7221e5a9 100644
--- a/src/generic/Collect.cpp
+++ b/src/generic/Collect.cpp
@@ -62,7 +62,8 @@ PLUMED_REGISTER_ACTION(Collect,"COLLECT")
 void Collect::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
   ActionWithArguments::registerKeywords( keys ); ActionPilot::registerKeywords( keys );
-  keys.use("ARG"); keys.use("UPDATE_FROM"); keys.use("UPDATE_UNTIL");
+  keys.use("UPDATE_FROM"); keys.use("UPDATE_UNTIL");
+  keys.addInputKeyword("compulsory","ARG","scalar/vector/matrix","the label of the value whose time series is being stored for later analysis");
   keys.add("compulsory","STRIDE","1","the frequency with which the data should be collected and added to the quantity being averaged");
   keys.add("compulsory","CLEAR","0","the frequency with which to clear all the accumulated data.  The default value "
            "of 0 implies that all the data will be used and that the grid will never be cleared");
diff --git a/src/generic/Committor.cpp b/src/generic/Committor.cpp
index 20ed416c21..6944f57ec8 100644
--- a/src/generic/Committor.cpp
+++ b/src/generic/Committor.cpp
@@ -80,7 +80,7 @@ void Committor::registerKeywords( Keywords& keys ) {
   Action::registerKeywords(keys);
   ActionPilot::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the values which is being used to define the committor surface");
   keys.add("numbered", "BASIN_LL","List of lower limits for basin #");
   keys.add("numbered", "BASIN_UL","List of upper limits for basin #");
   keys.reset_style("BASIN_LL","compulsory"); keys.reset_style("BASIN_UL","compulsory");
diff --git a/src/generic/CreateMask.cpp b/src/generic/CreateMask.cpp
index b94096f669..ae5bcdd919 100644
--- a/src/generic/CreateMask.cpp
+++ b/src/generic/CreateMask.cpp
@@ -56,7 +56,8 @@ PLUMED_REGISTER_ACTION(CreateMask,"CREATE_MASK")
 
 void CreateMask::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","vector","the label of the vector that you would like to construct a mask for");
   keys.add("compulsory","TYPE","the way the zeros are supposed to be set");
   keys.add("compulsory","NZEROS","the number of zeros that you want to put in the mask");
   keys.add("optional","SEED","the seed to use for the random number generator");
diff --git a/src/generic/DumpAtoms.cpp b/src/generic/DumpAtoms.cpp
index 3db26f4a9f..2ee63cd5ba 100644
--- a/src/generic/DumpAtoms.cpp
+++ b/src/generic/DumpAtoms.cpp
@@ -152,7 +152,8 @@ void DumpAtoms::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys );
   ActionPilot::registerKeywords( keys );
   ActionAtomistic::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("optional","ARG","vector","the labels of vectors that should be output in the xyz file. The number of elements in the vector should equal the number of atoms output");
   keys.add("compulsory","STRIDE","1","the frequency with which the atoms should be output");
   keys.add("atoms", "ATOMS", "the atom indices whose positions you would like to print out");
   keys.add("compulsory", "FILE", "file on which to output coordinates; extension is automatically detected");
diff --git a/src/generic/DumpDerivatives.cpp b/src/generic/DumpDerivatives.cpp
index e359bcf057..ddd91e9277 100644
--- a/src/generic/DumpDerivatives.cpp
+++ b/src/generic/DumpDerivatives.cpp
@@ -74,7 +74,7 @@ void DumpDerivatives::registerKeywords(Keywords& keys) {
   Action::registerKeywords(keys);
   ActionPilot::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the values whose derivatives should be output");
   keys.add("compulsory","STRIDE","1","the frequency with which the derivatives should be output");
   keys.add("compulsory","FILE","the name of the file on which to output the derivatives");
   keys.add("compulsory","FMT","%15.10f","the format with which the derivatives should be output");
diff --git a/src/generic/DumpForces.cpp b/src/generic/DumpForces.cpp
index 8fc1411f63..36c562dace 100644
--- a/src/generic/DumpForces.cpp
+++ b/src/generic/DumpForces.cpp
@@ -72,7 +72,7 @@ void DumpForces::registerKeywords(Keywords& keys) {
   Action::registerKeywords(keys);
   ActionPilot::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the values whose forces should be output");
   keys.add("compulsory","STRIDE","1","the frequency with which the forces should be output");
   keys.add("compulsory","FILE","the name of the file on which to output the forces");
   keys.add("compulsory","FMT","%15.10f","the format with which the derivatives should be output");
diff --git a/src/generic/DumpPDB.cpp b/src/generic/DumpPDB.cpp
index 7ab771d0ee..714b43aca1 100644
--- a/src/generic/DumpPDB.cpp
+++ b/src/generic/DumpPDB.cpp
@@ -67,7 +67,8 @@ PLUMED_REGISTER_ACTION(DumpPDB,"DUMPPDB")
 void DumpPDB::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys );
   ActionPilot::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("optional","ARG","vector/matrix","the values that are being output in the PDB file");
   keys.add("optional","ATOMS","value containing positions of atoms that should be output");
   keys.add("compulsory","STRIDE","0","the frequency with which the atoms should be output");
   keys.add("compulsory","FILE","the name of the file on which to output these quantities");
diff --git a/src/generic/DumpProjections.cpp b/src/generic/DumpProjections.cpp
index 87d02d7a18..d3a139fef9 100644
--- a/src/generic/DumpProjections.cpp
+++ b/src/generic/DumpProjections.cpp
@@ -70,7 +70,7 @@ void DumpProjections::registerKeywords(Keywords& keys) {
   Action::registerKeywords(keys);
   ActionPilot::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the values whose gradients should be outpu");
   keys.add("compulsory","STRIDE","1","the frequency with which the derivatives should be output");
   keys.add("compulsory","FILE","the name of the file on which to output the derivatives");
   keys.add("compulsory","FMT","%15.10f","the format with which the derivatives should be output");
diff --git a/src/generic/DumpVector.cpp b/src/generic/DumpVector.cpp
index 51f3b7a963..8985d09211 100644
--- a/src/generic/DumpVector.cpp
+++ b/src/generic/DumpVector.cpp
@@ -61,7 +61,8 @@ PLUMED_REGISTER_ACTION(DumpVector,"DUMPVECTOR")
 void DumpVector::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys );
   ActionPilot::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","vector/matrix","the labels of vectors/matrices that should be output in the file");
   keys.add("compulsory","STRIDE","0","the frequency with which the grid should be output to the file.");
   keys.add("compulsory","FILE","density","the file on which to write the vetors");
   keys.add("optional","FMT","the format that should be used to output real numbers");
diff --git a/src/generic/GatherReplicas.cpp b/src/generic/GatherReplicas.cpp
index fa093e303b..6575312f8f 100644
--- a/src/generic/GatherReplicas.cpp
+++ b/src/generic/GatherReplicas.cpp
@@ -54,7 +54,7 @@ PLUMED_REGISTER_ACTION(GatherReplicas,"GATHER_REPLICAS")
 
 void GatherReplicas::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys ); ActionWithArguments::registerKeywords( keys );
-  keys.remove("ARG"); keys.add("compulsory","ARG","the argument from the various replicas that you would like to gather");
+  keys.addInputKeyword("compulsory","ARG","scalar/vector/matrix/grid","the argument from the various replicas that you would like to gather");
   keys.addOutputComponent("rep","default","scalar/vector/matrix/grid","the input arguments for each of the replicas");
 }
 
diff --git a/src/generic/PDB2Constant.cpp b/src/generic/PDB2Constant.cpp
index b587ec03c9..fd58a312b6 100644
--- a/src/generic/PDB2Constant.cpp
+++ b/src/generic/PDB2Constant.cpp
@@ -50,7 +50,7 @@ void PDB2Constant::registerKeywords(Keywords& keys) {
   keys.add("compulsory","REFERENCE","a file in pdb format containing the reference structure");
   keys.add("compulsory","NUMBER","0","if there are multiple structures in the pdb file you can specify that you want the RMSD from a specific structure by specifying its place in the file here. If NUMBER=0 then the RMSD from all structures are computed");
   keys.addFlag("NOARGS",false,"the arguments that are being read from the PDB file are not in the plumed input");
-  keys.add("optional","ARG","read this single argument from the input rather than the atomic structure");
+  keys.addInputKeyword("optional","ARG","scalar/vector","read this single argument from the input rather than the atomic structure");
   keys.setValueDescription("scalar/vector/matrix","a value that is constructed from the information in the PDB file");
   keys.needsAction("CONSTANT");
 }
diff --git a/src/generic/Print.cpp b/src/generic/Print.cpp
index 4f3ca3bfdf..603c633bdc 100644
--- a/src/generic/Print.cpp
+++ b/src/generic/Print.cpp
@@ -99,7 +99,7 @@ void Print::registerKeywords(Keywords& keys) {
   Action::registerKeywords(keys);
   ActionPilot::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("compulsory","ARG","scalar/vector/matrix","the labels of the values that you would like to print to the file");
   keys.add("compulsory","STRIDE","1","the frequency with which the quantities of interest should be output");
   keys.add("optional","FILE","the name of the file on which to output these quantities");
   keys.add("optional","FMT","the format that should be used to output real numbers");
diff --git a/src/generic/PrintNDX.cpp b/src/generic/PrintNDX.cpp
index afe4a25116..ce2d533fe5 100644
--- a/src/generic/PrintNDX.cpp
+++ b/src/generic/PrintNDX.cpp
@@ -66,7 +66,7 @@ void PrintNDX::registerKeywords(Keywords& keys) {
   ActionPilot::registerKeywords(keys);
   ActionAtomistic::registerKeywords( keys );
   ActionWithArguments::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("optional","ARG","vector","the labels of vectors that should be used when printind the NDX file");
   keys.add("atoms","ATOMS","the list of atoms that have the corresponding arguments");
   keys.add("compulsory","STRIDE","1","the frequency with which the quantities of interest should be output");
   keys.add("optional","FILE","the name of the file on which to output these quantities");
diff --git a/src/generic/UpdateIf.cpp b/src/generic/UpdateIf.cpp
index a7abb36d04..331e572364 100644
--- a/src/generic/UpdateIf.cpp
+++ b/src/generic/UpdateIf.cpp
@@ -100,7 +100,7 @@ void UpdateIf::registerKeywords(Keywords& keys) {
   Action::registerKeywords(keys);
   ActionPilot::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of values that should be used to make the decision on whether to update or not");
   keys.add("compulsory","STRIDE","1","the frequency with which the quantities of interest should be output");
   keys.addFlag("END",false,"end");
   keys.add("optional","LESS_THAN","upper bound");
diff --git a/src/gridtools/DumpGrid.cpp b/src/gridtools/DumpGrid.cpp
index d6eedd3277..791150e4be 100644
--- a/src/gridtools/DumpGrid.cpp
+++ b/src/gridtools/DumpGrid.cpp
@@ -198,7 +198,8 @@ PLUMED_REGISTER_ACTION(DumpGrid,"DUMPGRID")
 void DumpGrid::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys );
   ActionPilot::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","grid","the label for the grid that you would like to output");
   keys.add("optional","GRID","the grid you would like to print (can also use ARG for specifying what is being printed)");
   keys.add("compulsory","STRIDE","0","the frequency with which the grid should be output to the file.  Default of zero means dump at end of calculation");
   keys.add("compulsory","FILE","density","the file on which to write the grid.");
diff --git a/src/gridtools/EvaluateFunctionOnGrid.cpp b/src/gridtools/EvaluateFunctionOnGrid.cpp
index 9add313e8f..aaf0b29a76 100644
--- a/src/gridtools/EvaluateFunctionOnGrid.cpp
+++ b/src/gridtools/EvaluateFunctionOnGrid.cpp
@@ -71,8 +71,8 @@ PLUMED_REGISTER_ACTION(VectorEvalGrid,"EVALUATE_FUNCTION_FROM_GRID_VECTOR")
 
 void EvaluateFunctionOnGrid::registerKeywords(Keywords& keys ) {
   ActionShortcut::registerKeywords( keys );
-  keys.add("compulsory","GRID","the name of the grid that we are using to evaluate the function");
-  keys.add("optional","ARG","the arguments that you would like to use when evaluating the function.  If not specified these are determined from the names of the grid dimensions");
+  keys.addInputKeyword("compulsory","GRID","grid","the name of the grid that we are using to evaluate the function");
+  keys.addInputKeyword("optional","ARG","scalar/vector","the arguments that you would like to use when evaluating the function.  If not specified these are determined from the names of the grid dimensions");
   keys.reserve("compulsory","PERIODIC","if the output of your function is periodic then you should specify the periodicity of the function.  If the output is not periodic you must state this using PERIODIC=NO");
   EvaluateGridFunction ii; ii.registerKeywords( keys );
   keys.addActionNameSuffix("_SCALAR"); keys.addActionNameSuffix("_VECTOR");
diff --git a/src/gridtools/FindGridOptimum.cpp b/src/gridtools/FindGridOptimum.cpp
index 429120c160..a2d946a40b 100644
--- a/src/gridtools/FindGridOptimum.cpp
+++ b/src/gridtools/FindGridOptimum.cpp
@@ -67,7 +67,8 @@ PLUMED_REGISTER_ACTION(FindGridOptimum,"FIND_GRID_MAXIMUM")
 PLUMED_REGISTER_ACTION(FindGridOptimum,"FIND_GRID_MINIMUM")
 
 void FindGridOptimum::registerKeywords( Keywords& keys ) {
-  ActionWithGrid::registerKeywords( keys ); keys.use("ARG");
+  ActionWithGrid::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","grid","the label for the function on the grid that you would like to find the optimum in");
   keys.addFlag("NOINTERPOL",false,"do not interpolate the function when finding the optimum");
   keys.add("compulsory","CGTOL","1E-4","the tolerance for the conjugate gradient optimization");
   keys.addOutputComponent("optval","default","scalar","the value of the function at the optimum");
diff --git a/src/gridtools/FunctionOfGrid.h b/src/gridtools/FunctionOfGrid.h
index 33bebe6d7e..efa417408c 100644
--- a/src/gridtools/FunctionOfGrid.h
+++ b/src/gridtools/FunctionOfGrid.h
@@ -58,16 +58,19 @@ class FunctionOfGrid : public ActionWithGrid {
 
 template <class T>
 void FunctionOfGrid<T>::registerKeywords(Keywords& keys ) {
-  ActionWithGrid::registerKeywords(keys); keys.use("ARG"); std::string name = keys.getDisplayName();
+  ActionWithGrid::registerKeywords(keys); std::string name = keys.getDisplayName();
   std::size_t und=name.find("_GRID"); keys.setDisplayName( name.substr(0,und) );
   keys.reserve("compulsory","PERIODIC","if the output of your function is periodic then you should specify the periodicity of the function.  If the output is not periodic you must state this using PERIODIC=NO");
   T tfunc; tfunc.registerKeywords( keys ); if( typeid(tfunc)==typeid(function::Custom()) ) keys.add("hidden","NO_ACTION_LOG","suppresses printing from action on the log");
   if( keys.getDisplayName()=="INTEGRATE") {
     keys.setValueDescription("scalar","the numerical integral of the input function over its whole domain");
+    keys.addInputKeyword("compulsory","ARG","grid","the label of the function on a grid that is being integrated");
   } else if( keys.getDisplayName()=="SUM") {
     keys.setValueDescription("scalar","the sum of the value of the function over all the grid points where it has been evaluated");
+    keys.addInputKeyword("compulsory","ARG","grid","the label of the function on a grid from which we are computing a sum");
   } else if( keys.outputComponentExists(".#!value") ) {
     keys.setValueDescription("grid","the grid obtained by doing an element-wise application of " + keys.getOutputComponentDescription(".#!value") + " to the input grid");
+    keys.addInputKeyword("compulsory","ARG","scalar/grid","the labels of the scalars and functions on a grid that we are using to compute the required function");
   }
 }
 
diff --git a/src/gridtools/Histogram.cpp b/src/gridtools/Histogram.cpp
index 614fe73df4..b8b1d15a4f 100644
--- a/src/gridtools/Histogram.cpp
+++ b/src/gridtools/Histogram.cpp
@@ -204,7 +204,7 @@ PLUMED_REGISTER_ACTION(Histogram,"HISTOGRAM")
 void Histogram::registerKeywords( Keywords& keys ) {
   ActionShortcut::registerKeywords( keys ); keys.use("UPDATE_FROM"); keys.use("UPDATE_UNTIL");
   keys.add("compulsory","NORMALIZATION","ndata","This controls how the data is normalized it can be set equal to true, false or ndata.  See above for an explanation");
-  keys.add("optional","ARG","the quantity that is being averaged");
+  keys.addInputKeyword("optional","ARG","scalar/vector/matrix","the quantities that are being used to construct the histogram");
   keys.add("optional","DATA","an alternative to the ARG keyword");
   keys.add("compulsory","GRID_MIN","auto","the lower bounds for the grid");
   keys.add("compulsory","GRID_MAX","auto","the upper bounds for the grid");
diff --git a/src/gridtools/InterpolateGrid.cpp b/src/gridtools/InterpolateGrid.cpp
index bab2a08477..603da9c138 100644
--- a/src/gridtools/InterpolateGrid.cpp
+++ b/src/gridtools/InterpolateGrid.cpp
@@ -75,7 +75,8 @@ PLUMED_REGISTER_ACTION(InterpolateGrid,"INTERPOLATE_GRID")
 
 void InterpolateGrid::registerKeywords( Keywords& keys ) {
   ActionWithGrid::registerKeywords( keys );
-  keys.add("optional","GRID_BIN","the number of bins for the grid"); keys.use("ARG");
+  keys.add("optional","GRID_BIN","the number of bins for the grid");
+  keys.addInputKeyword("compulsory","ARG","grid","the label for function on the grid that you would like to interpolate");
   keys.add("optional","GRID_SPACING","the approximate grid spacing (to be used as an alternative or together with GRID_BIN)");
   keys.addFlag("MIDPOINTS",false,"interpolate the values of the function at the midpoints of the grid coordinates of the input grid");
   EvaluateGridFunction ii; ii.registerKeywords( keys );
diff --git a/src/gridtools/KDE.cpp b/src/gridtools/KDE.cpp
index b9f1d5011f..90d499275d 100644
--- a/src/gridtools/KDE.cpp
+++ b/src/gridtools/KDE.cpp
@@ -94,7 +94,8 @@ PLUMED_REGISTER_ACTION(KDE,"KDE")
 PLUMED_REGISTER_ACTION(KDE,"SPHERICAL_KDE")
 
 void KDE::registerKeywords( Keywords& keys ) {
-  ActionWithGrid::registerKeywords( keys ); keys.use("ARG");
+  ActionWithGrid::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","scalar/vector/matrix","the label for the value that should be used to construct the histogram");
   keys.add("optional","HEIGHTS","this keyword takes the label of an action that calculates a vector of values.  The elements of this vector "
            "are used as weights for the Gaussians.");
   keys.add("optional","VOLUMES","this keyword take the label of an action that calculates a vector of values.  The elements of this vector "
diff --git a/src/isdb/Caliber.cpp b/src/isdb/Caliber.cpp
index ade29b488b..6794060d04 100644
--- a/src/isdb/Caliber.cpp
+++ b/src/isdb/Caliber.cpp
@@ -124,7 +124,6 @@ PLUMED_REGISTER_ACTION(Caliber,"CALIBER")
 
 void Caliber::registerKeywords( Keywords& keys ) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.addFlag("NOENSEMBLE",false,"don't perform any replica-averaging");
   keys.add("compulsory","FILE","the name of the file containing the time-resolved values");
   keys.add("compulsory","KAPPA","a force constant, this can be use to scale a constant estimated on-the-fly using AVERAGING");
diff --git a/src/isdb/EMMI.cpp b/src/isdb/EMMI.cpp
index 01187721d4..699b5cfad1 100644
--- a/src/isdb/EMMI.cpp
+++ b/src/isdb/EMMI.cpp
@@ -389,7 +389,7 @@ void EMMI::registerKeywords( Keywords& keys ) {
   ActionAtomistic::registerKeywords( keys );
   ActionWithValue::registerKeywords( keys );
   ActionWithArguments::registerKeywords( keys );
-  keys.use("ARG");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the values from which the function is calculated");
   keys.add("atoms","ATOMS","atoms for which we calculate the density map, typically all heavy atoms");
   keys.addFlag("NOPBC",false,"ignore the periodic boundary conditions when calculating distances");
   keys.add("compulsory","GMM_FILE","file with the parameters of the GMM components");
diff --git a/src/isdb/Metainference.cpp b/src/isdb/Metainference.cpp
index 422df13526..7ccd93b60f 100644
--- a/src/isdb/Metainference.cpp
+++ b/src/isdb/Metainference.cpp
@@ -286,8 +286,7 @@ PLUMED_REGISTER_ACTION(Metainference,"METAINFERENCE")
 
 void Metainference::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
-  keys.add("optional","PARARG","reference values for the experimental data, these can be provided as arguments without derivatives");
+  keys.addInputKeyword("optional","PARARG","scalar","reference values for the experimental data, these can be provided as arguments without derivatives");
   keys.add("optional","PARAMETERS","reference values for the experimental data");
   keys.addFlag("NOENSEMBLE",false,"don't perform any replica-averaging");
   keys.addFlag("REWEIGHT",false,"simple REWEIGHT using the latest ARG as energy");
diff --git a/src/isdb/MetainferenceBase.cpp b/src/isdb/MetainferenceBase.cpp
index 39230165bd..6059b48f5c 100644
--- a/src/isdb/MetainferenceBase.cpp
+++ b/src/isdb/MetainferenceBase.cpp
@@ -36,7 +36,7 @@ void MetainferenceBase::registerKeywords( Keywords& keys ) {
   ActionAtomistic::registerKeywords(keys);
   ActionWithValue::registerKeywords(keys);
   ActionWithArguments::registerKeywords(keys);
-  keys.use("ARG");
+  keys.addInputKeyword("optional","ARG","scalar","the labels of the values from which the function is calculated");
   keys.addFlag("DOSCORE",false,"activate metainference");
   keys.addFlag("NOENSEMBLE",false,"don't perform any replica-averaging");
   keys.addFlag("REWEIGHT",false,"simple REWEIGHT using the ARG as energy");
diff --git a/src/isdb/Rescale.cpp b/src/isdb/Rescale.cpp
index 6963c5728e..750463398e 100644
--- a/src/isdb/Rescale.cpp
+++ b/src/isdb/Rescale.cpp
@@ -163,7 +163,6 @@ PLUMED_REGISTER_ACTION(Rescale,"RESCALE")
 
 void Rescale::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","TEMP","temperature");
   keys.add("compulsory","SELECTOR", "name of the SELECTOR used for rescaling");
   keys.add("compulsory","MAX_RESCALE","maximum values for rescaling");
diff --git a/src/isdb/Select.cpp b/src/isdb/Select.cpp
index f271c873d8..f7afb8d0e6 100644
--- a/src/isdb/Select.cpp
+++ b/src/isdb/Select.cpp
@@ -80,7 +80,6 @@ PLUMED_REGISTER_ACTION(Select,"SELECT")
 
 void Select::registerKeywords(Keywords& keys) {
   Function::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","SELECTOR","name of the variable used to select");
   keys.setValueDescription("scalar","the value of the selected argument");
 }
diff --git a/src/landmarks/CollectFrames.cpp b/src/landmarks/CollectFrames.cpp
index 961dbf18f0..8ef6c8a8dc 100644
--- a/src/landmarks/CollectFrames.cpp
+++ b/src/landmarks/CollectFrames.cpp
@@ -49,10 +49,10 @@ PLUMED_REGISTER_ACTION(CollectFrames,"COLLECT_FRAMES")
 
 void CollectFrames::registerKeywords( Keywords& keys ) {
   ActionShortcut::registerKeywords( keys );
+  keys.addInputKeyword("optional","ARG","scalar/vector","the labels of the values whose time series you would like to collect for later analysis");
   keys.add("compulsory","STRIDE","1","the frequency with which data should be stored for analysis.  By default data is collected on every step");
   keys.add("compulsory","CLEAR","0","the frequency with which data should all be deleted and restarted");
   keys.add("compulsory","ALIGN","OPTIMAL","if storing atoms how would you like the alignment to be done can be SIMPLE/OPTIMAL");
-  keys.add("optional","ARG","the arguments you would like to collect");
   keys.add("optional","ATOMS","list of atomic positions that you would like to collect and store for later analysis");
   keys.add("optional","LOGWEIGHTS","list of actions that calculates log weights that should be used to weight configurations when calculating averages");
   keys.addOutputComponent("data","default","matrix","the data that is being collected by this action");
diff --git a/src/logmfd/LogMFD.cpp b/src/logmfd/LogMFD.cpp
index 754dcd2fd0..9748eef0b6 100644
--- a/src/logmfd/LogMFD.cpp
+++ b/src/logmfd/LogMFD.cpp
@@ -461,7 +461,6 @@ PLUMED_REGISTER_ACTION(LogMFD,"LOGMFD")
 */
 void LogMFD::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","INTERVAL",
            "Period of MD steps (N_m) to update fictitious dynamical variables." );
   keys.add("compulsory","DELTA_T",
diff --git a/src/mapping/GeometricPath.cpp b/src/mapping/GeometricPath.cpp
index 3ef9d0c0d4..578ebe3ec5 100644
--- a/src/mapping/GeometricPath.cpp
+++ b/src/mapping/GeometricPath.cpp
@@ -50,9 +50,9 @@ class GeometricPath : public ActionWithVector {
 PLUMED_REGISTER_ACTION(GeometricPath,"GEOMETRIC_PATH")
 
 void GeometricPath::registerKeywords(Keywords& keys) {
-  ActionWithVector::registerKeywords(keys); keys.use("ARG");
+  ActionWithVector::registerKeywords(keys);
   PathProjectionCalculator::registerKeywords(keys);
-  keys.add("compulsory","PROPERTY","the coordinates we are projecting these points onto");
+  keys.addInputKeyword("compulsory","PROPERTY","vector","the label of a value that contains the coordinates we are projecting these points onto");
   keys.addOutputComponent("s","default","scalar","the position on the path");
   keys.addOutputComponent("z","default","scalar","the distance from the path");
   keys.needsAction("GEOMETRIC_PATH"); keys.needsAction("PDB2CONSTANT");
diff --git a/src/mapping/PCAVars.cpp b/src/mapping/PCAVars.cpp
index b3fe022e21..099bc96b9e 100644
--- a/src/mapping/PCAVars.cpp
+++ b/src/mapping/PCAVars.cpp
@@ -181,7 +181,7 @@ void PCAVars::registerKeywords( Keywords& keys ) {
   keys.add("compulsory","TYPE","OPTIMAL-FAST","the manner in which distances are calculated. More information on the different "
            "metrics that are available in PLUMED can be found in the section of the manual on "
            "\\ref dists");
-  keys.add("optional","ARG","if there are arguments to be used specify them here");
+  keys.addInputKeyword("optional","ARG","scalar/vector","if there are arguments to be used specify them here");
   keys.addFlag("NOPBC",false,"do not use periodic boundary conditions when computing this quantity");
   keys.addOutputComponent("eig","default","vector","the projections on the eigenvalues");
   keys.addOutputComponent("residual","default","scalar","the residual distance that is not projected on any of the eigenvalues");
diff --git a/src/mapping/Path.cpp b/src/mapping/Path.cpp
index c60f98dd5a..0d3f23cea5 100644
--- a/src/mapping/Path.cpp
+++ b/src/mapping/Path.cpp
@@ -223,7 +223,7 @@ void Path::registerInputFileKeywords( Keywords& keys ) {
   keys.add("compulsory","TYPE","OPTIMAL-FAST","the manner in which distances are calculated. More information on the different "
            "metrics that are available in PLUMED can be found in the section of the manual on "
            "\\ref dists");
-  keys.add("optional","ARG","the list of arguments you would like to use in your definition of the path");
+  keys.addInputKeyword("optional","ARG","scalar","the list of arguments you would like to use in your definition of the path");
   keys.add("optional","COEFFICIENTS","the coefficients of the displacements along each argument that should be used when calculating the euclidean distance");
   keys.addFlag("NOPBC",false,"ignore the periodic boundary conditions when calculating distances");
   keys.addFlag("NOSPATH",false,"do not calculate the spath CV");
diff --git a/src/mapping/PathDisplacements.cpp b/src/mapping/PathDisplacements.cpp
index d4ec2eea0a..f6609175c7 100644
--- a/src/mapping/PathDisplacements.cpp
+++ b/src/mapping/PathDisplacements.cpp
@@ -60,7 +60,7 @@ PLUMED_REGISTER_ACTION(PathDisplacements,"AVERAGE_PATH_DISPLACEMENT")
 
 void PathDisplacements::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys ); ActionPilot::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG"); PathProjectionCalculator::registerKeywords( keys );
+  ActionWithArguments::registerKeywords( keys ); PathProjectionCalculator::registerKeywords( keys );
   keys.add("compulsory","STRIDE","1","the frequency with which the average displacements should be collected and added to the average displacements");
   keys.add("compulsory","HALFLIFE","-1","the number of MD steps after which a previously measured path distance weighs only 50 percent in the average. This option may increase convergence by allowing to forget the memory of a bad initial guess path. The default is to set this to infinity");
   keys.add("compulsory","CLEAR","0","the frequency with which to clear all the accumulated data.  The default value "
diff --git a/src/mapping/PathProjectionCalculator.cpp b/src/mapping/PathProjectionCalculator.cpp
index fe22867246..606d319bbb 100644
--- a/src/mapping/PathProjectionCalculator.cpp
+++ b/src/mapping/PathProjectionCalculator.cpp
@@ -30,9 +30,10 @@ namespace PLMD {
 namespace mapping {
 
 void PathProjectionCalculator::registerKeywords(Keywords& keys) {
+  keys.addInputKeyword("compulsory","ARG","matrix","the labels of the matrix that contains the vectors of displacements from each frame in the path");
   keys.add("compulsory","METRIC","the method to use for computing the displacement vectors between the reference frames");
   keys.add("compulsory","METRIC_COMPONENT","if the final action in your metric contains multiple components this keyword is used to specify the component that should be used");
-  keys.add("compulsory","REFERENCE","labels for actions that contain reference coordinates for each point on the path");
+  keys.addInputKeyword("compulsory","REFERENCE","vector","labels for actions that contain reference coordinates for each point on the path");
 }
 
 PathProjectionCalculator::PathProjectionCalculator( Action* act ):
diff --git a/src/matrixtools/Determinent.cpp b/src/matrixtools/Determinent.cpp
index c673b66dfd..5a2c023da8 100644
--- a/src/matrixtools/Determinent.cpp
+++ b/src/matrixtools/Determinent.cpp
@@ -44,7 +44,7 @@ PLUMED_REGISTER_ACTION(Determinant,"DETERMINANT")
 
 void Determinant::registerKeywords( Keywords& keys ) {
   ActionShortcut::registerKeywords(keys);
-  keys.add("compulsory","ARG","The matrix that we are calculating the determinant for");
+  keys.addInputKeyword("compulsory","ARG","matrix","The matrix that we are calculating the determinant for");
   keys.setValueDescription("scalar","the determinant of the matrix");
 }
 
diff --git a/src/matrixtools/MatrixOperationBase.cpp b/src/matrixtools/MatrixOperationBase.cpp
index e2b2a4d7b0..ce719eab53 100644
--- a/src/matrixtools/MatrixOperationBase.cpp
+++ b/src/matrixtools/MatrixOperationBase.cpp
@@ -26,7 +26,8 @@ namespace matrixtools {
 
 void MatrixOperationBase::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithArguments::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
-  keys.use("ARG"); keys.remove("NUMERICAL_DERIVATIVES");
+  keys.addInputKeyword("compulsory","ARG","matrix","the input matrix");
+  keys.remove("NUMERICAL_DERIVATIVES");
   keys.add("optional","MATRIX","the input matrix (can use ARG instead)");
 }
 
diff --git a/src/matrixtools/MatrixTimesMatrix.cpp b/src/matrixtools/MatrixTimesMatrix.cpp
index 6ae5590fcd..8840354dc1 100644
--- a/src/matrixtools/MatrixTimesMatrix.cpp
+++ b/src/matrixtools/MatrixTimesMatrix.cpp
@@ -64,7 +64,8 @@ PLUMED_REGISTER_ACTION(MatrixTimesMatrix,"MATRIX_PRODUCT")
 PLUMED_REGISTER_ACTION(MatrixTimesMatrix,"DISSIMILARITIES")
 
 void MatrixTimesMatrix::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords(keys); keys.use("ARG");
+  ActionWithMatrix::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","matrix","the label of the two matrices from which the product is calculated");
   keys.addFlag("SQUARED",false,"calculate the squares of the dissimilarities (this option cannot be used with MATRIX_PRODUCT)");
   keys.setValueDescription("matrix","the product of the two input matrices");
 }
diff --git a/src/matrixtools/MatrixTimesVector.cpp b/src/matrixtools/MatrixTimesVector.cpp
index 2ef142dac0..fe8c3ed498 100644
--- a/src/matrixtools/MatrixTimesVector.cpp
+++ b/src/matrixtools/MatrixTimesVector.cpp
@@ -56,7 +56,8 @@ class MatrixTimesVector : public ActionWithMatrix {
 PLUMED_REGISTER_ACTION(MatrixTimesVector,"MATRIX_VECTOR_PRODUCT")
 
 void MatrixTimesVector::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords(keys); keys.use("ARG");
+  ActionWithMatrix::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","matrix/vector/scalar","the label for the matrix and the vector/scalar that are being multiplied.  Alternatively, you can provide labels for multiple matrices and a single vector or labels for a single matrix and multiple vectors. In these cases multiple matrix vector products will be computed.");
   keys.setValueDescription("vector","the vector that is obtained by taking the product between the matrix and the vector that were input");
   ActionWithValue::useCustomisableComponents(keys);
 }
diff --git a/src/matrixtools/OuterProduct.cpp b/src/matrixtools/OuterProduct.cpp
index 8fcd804f42..518927003a 100644
--- a/src/matrixtools/OuterProduct.cpp
+++ b/src/matrixtools/OuterProduct.cpp
@@ -55,7 +55,8 @@ class OuterProduct : public ActionWithMatrix {
 PLUMED_REGISTER_ACTION(OuterProduct,"OUTER_PRODUCT")
 
 void OuterProduct::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords(keys); keys.use("ARG");
+  ActionWithMatrix::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","vector","the labels of the two vectors from which the outer product is being computed");
   keys.add("compulsory","FUNC","x*y","the function of the input vectors that should be put in the elements of the outer product");
   keys.addFlag("ELEMENTS_ON_DIAGONAL_ARE_ZERO",false,"set all diagonal elements to zero");
   keys.setValueDescription("matrix","a matrix containing the outer product of the two input vectors that was obtained using the function that was input");
diff --git a/src/matrixtools/TransposeMatrix.cpp b/src/matrixtools/TransposeMatrix.cpp
index 1047073262..92b23da488 100644
--- a/src/matrixtools/TransposeMatrix.cpp
+++ b/src/matrixtools/TransposeMatrix.cpp
@@ -55,6 +55,7 @@ PLUMED_REGISTER_ACTION(TransposeMatrix,"TRANSPOSE")
 
 void TransposeMatrix::registerKeywords( Keywords& keys ) {
   MatrixOperationBase::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","vector/matrix","the label of the vector or matrix that should be transposed");
   keys.setValueDescription("vector/matrix","the transpose of the input matrix");
 }
 
diff --git a/src/matrixtools/Voronoi.cpp b/src/matrixtools/Voronoi.cpp
index 3ac9817e04..a28b074c2c 100644
--- a/src/matrixtools/Voronoi.cpp
+++ b/src/matrixtools/Voronoi.cpp
@@ -51,7 +51,8 @@ class Voronoi : public ActionWithMatrix {
 PLUMED_REGISTER_ACTION(Voronoi,"VORONOI")
 
 void Voronoi::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords(keys); keys.use("ARG");
+  ActionWithMatrix::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","matrix","the distance/adjacency matrix that should be used to perform the voronoi analysis");
   keys.setValueDescription("matrix","a matrix in which element ij is equal to one if the ij component of the input matrix is lower than all the ik elements of the matrix where k is not j and zero otherwise");
 }
 
diff --git a/src/maze/Optimizer_Bias.cpp b/src/maze/Optimizer_Bias.cpp
index c6a39b58a5..1500346ef7 100644
--- a/src/maze/Optimizer_Bias.cpp
+++ b/src/maze/Optimizer_Bias.cpp
@@ -200,8 +200,6 @@ PLUMED_REGISTER_ACTION(OptimizerBias, "MAZE_OPTIMIZER_BIAS")
 void OptimizerBias::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
 
-  keys.use("ARG");
-
   keys.add(
     "compulsory",
     "BIASING_RATE",
diff --git a/src/opes/ECVcustom.cpp b/src/opes/ECVcustom.cpp
index 8e87f18b5c..62fd80b44d 100644
--- a/src/opes/ECVcustom.cpp
+++ b/src/opes/ECVcustom.cpp
@@ -87,8 +87,7 @@ PLUMED_REGISTER_ACTION(ECVcustom,"ECV_CUSTOM")
 void ECVcustom::registerKeywords(Keywords& keys)
 {
   ExpansionCVs::registerKeywords(keys);
-  keys.remove("ARG");
-  keys.add("compulsory","ARG","the labels of the single ECVs. Delta U_i, in energy units");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the single ECVs. Delta U_i, in energy units");
   keys.addFlag("ADD_P0",false,"add the unbiased Boltzmann distribution to the target distribution, to make sure to sample it");
   keys.addFlag("DIMENSIONLESS",false,"consider ARG as dimensionless rather than an energy, thus do not multiply it by beta");
   keys.add("optional","BARRIER","a guess of the free energy barrier to be overcome (better to stay higher than lower)");
diff --git a/src/opes/ECVlinear.cpp b/src/opes/ECVlinear.cpp
index 48650d607d..7375229ea0 100644
--- a/src/opes/ECVlinear.cpp
+++ b/src/opes/ECVlinear.cpp
@@ -97,8 +97,7 @@ PLUMED_REGISTER_ACTION(ECVlinear,"ECV_LINEAR")
 void ECVlinear::registerKeywords(Keywords& keys)
 {
   ExpansionCVs::registerKeywords(keys);
-  keys.remove("ARG");
-  keys.add("compulsory","ARG","the label of the Hamiltonian difference. Delta U");
+  keys.addInputKeyword("compulsory","ARG","scalar","the label of the Hamiltonian difference. Delta U");
   keys.add("compulsory","LAMBDA","0","the lambda at which the underlying simulation runs");
   keys.add("optional","LAMBDA_MIN","( default=0 ) the minimum of the lambda range");
   keys.add("optional","LAMBDA_MAX","( default=1 ) the maximum of the lambda range");
diff --git a/src/opes/ECVmultiThermal.cpp b/src/opes/ECVmultiThermal.cpp
index 9ab1ce1a49..1d7b22e2a5 100644
--- a/src/opes/ECVmultiThermal.cpp
+++ b/src/opes/ECVmultiThermal.cpp
@@ -103,8 +103,7 @@ PLUMED_REGISTER_ACTION(ECVmultiThermal,"ECV_MULTITHERMAL")
 void ECVmultiThermal::registerKeywords(Keywords& keys)
 {
   ExpansionCVs::registerKeywords(keys);
-  keys.remove("ARG");
-  keys.add("compulsory","ARG","the label of the internal energy of the system. If volume is fixed it is calculated by the ENERGY colvar");
+  keys.addInputKeyword("compulsory","ARG","scalar","the label of the internal energy of the system. If volume is fixed it is calculated by the ENERGY colvar");
   keys.add("optional","TEMP_MIN","the minimum of the temperature range");
   keys.add("optional","TEMP_MAX","the maximum of the temperature range");
   keys.add("optional","TEMP_STEPS","the number of steps in temperature");
diff --git a/src/opes/ECVmultiThermalBaric.cpp b/src/opes/ECVmultiThermalBaric.cpp
index 059fec82cc..614fea208f 100644
--- a/src/opes/ECVmultiThermalBaric.cpp
+++ b/src/opes/ECVmultiThermalBaric.cpp
@@ -110,8 +110,7 @@ PLUMED_REGISTER_ACTION(ECVmultiThermalBaric,"ECV_MULTITHERMAL_MULTIBARIC")
 void ECVmultiThermalBaric::registerKeywords(Keywords& keys)
 {
   ExpansionCVs::registerKeywords(keys);
-  keys.remove("ARG");
-  keys.add("compulsory","ARG","the labels of the potential energy and of the volume of the system. You can calculate them with ENERGY and VOLUME respectively");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the potential energy and of the volume of the system. You can calculate them with ENERGY and VOLUME respectively");
 //temperature
   keys.add("optional","TEMP_MIN","the minimum of the temperature range");
   keys.add("optional","TEMP_MAX","the maximum of the temperature range");
diff --git a/src/opes/ECVumbrellasFile.cpp b/src/opes/ECVumbrellasFile.cpp
index 6f1342bdd4..371dc78453 100644
--- a/src/opes/ECVumbrellasFile.cpp
+++ b/src/opes/ECVumbrellasFile.cpp
@@ -98,7 +98,6 @@ PLUMED_REGISTER_ACTION(ECVumbrellasFile,"ECV_UMBRELLAS_FILE")
 void ECVumbrellasFile::registerKeywords(Keywords& keys)
 {
   ExpansionCVs::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","FILE","the name of the file containing the umbrellas");
   keys.add("optional","BARRIER","a guess of the free energy barrier to be overcome (better to stay higher than lower)");
   keys.addFlag("ADD_P0",false,"add the unbiased Boltzmann distribution to the target distribution, to make sure to sample it");
diff --git a/src/opes/ECVumbrellasLine.cpp b/src/opes/ECVumbrellasLine.cpp
index 0ab817422f..dc9e455b8e 100644
--- a/src/opes/ECVumbrellasLine.cpp
+++ b/src/opes/ECVumbrellasLine.cpp
@@ -99,7 +99,6 @@ PLUMED_REGISTER_ACTION(ECVumbrellasLine,"ECV_UMBRELLAS_LINE")
 void ECVumbrellasLine::registerKeywords(Keywords& keys)
 {
   ExpansionCVs::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","CV_MIN","the minimum of the CV range to be explored");
   keys.add("compulsory","CV_MAX","the maximum of the CV range to be explored");
   keys.add("compulsory","SIGMA","sigma of the umbrella Gaussians");
diff --git a/src/opes/ExpansionCVs.cpp b/src/opes/ExpansionCVs.cpp
index 4d2b3632c9..e2e9c8663a 100644
--- a/src/opes/ExpansionCVs.cpp
+++ b/src/opes/ExpansionCVs.cpp
@@ -30,6 +30,7 @@ void ExpansionCVs::registerKeywords(Keywords& keys)
   ActionWithArguments::registerKeywords(keys);
   ActionWithValue::useCustomisableComponents(keys);
   keys.add("compulsory","TEMP","-1","temperature. If not specified tries to get it from MD engine");
+  keys.addInputKeyword("compulsory","ARG","scalar","the labels of the scalar values that are input to this action");
 }
 
 ExpansionCVs::ExpansionCVs(const ActionOptions&ao)
diff --git a/src/opes/OPESexpanded.cpp b/src/opes/OPESexpanded.cpp
index 4d63004b46..ab2c118bec 100644
--- a/src/opes/OPESexpanded.cpp
+++ b/src/opes/OPESexpanded.cpp
@@ -181,8 +181,7 @@ PLUMED_REGISTER_ACTION(OPESexpanded,"OPES_EXPANDED")
 void OPESexpanded::registerKeywords(Keywords& keys)
 {
   Bias::registerKeywords(keys);
-  keys.remove("ARG");
-  keys.add("compulsory","ARG","the label of the ECVs that define the expansion. You can use an * to make sure all the output components of the ECVs are used, as in the examples above");
+  keys.addInputKeyword("compulsory","ARG","scalar","the label of the ECVs that define the expansion. You can use an * to make sure all the output components of the ECVs are used, as in the examples above");
   keys.add("compulsory","PACE","how often the bias is updated");
   keys.add("compulsory","OBSERVATION_STEPS","100","number of unbiased initial PACE steps to collect statistics for initialization");
 //DeltaFs and state files
diff --git a/src/opes/OPESmetad.cpp b/src/opes/OPESmetad.cpp
index cea53924cb..00eb8a743f 100644
--- a/src/opes/OPESmetad.cpp
+++ b/src/opes/OPESmetad.cpp
@@ -302,7 +302,6 @@ template <class mode>
 void OPESmetad<mode>::registerKeywords(Keywords& keys)
 {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("compulsory","TEMP","-1","temperature. If not set, it is taken from MD engine, but not all MD codes provide it");
   keys.add("compulsory","PACE","the frequency for kernel deposition");
   std::string info_sigma("the initial widths of the kernels");
@@ -337,9 +336,9 @@ void OPESmetad<mode>::registerKeywords(Keywords& keys)
   keys.add("optional","STATE_WSTRIDE","number of MD steps between writing the STATE_WFILE. Default is only on CPT events (but not all MD codes set them)");
   keys.addFlag("STORE_STATES",false,"append to STATE_WFILE instead of ovewriting it each time");
 //miscellaneous
-  keys.add("optional","EXCLUDED_REGION","kernels are not deposited when the action provided here has a nonzero value, see example above");
+  keys.addInputKeyword("optional","EXCLUDED_REGION","scalar","kernels are not deposited when the action provided here has a nonzero value, see example above");
   if(!mode::explore)
-    keys.add("optional","EXTRA_BIAS","consider also these other bias potentials for the internal reweighting. This can be used e.g. for sampling a custom target distribution (see example above)");
+    keys.addInputKeyword("optional","EXTRA_BIAS","scalar","consider also these other bias potentials for the internal reweighting. This can be used e.g. for sampling a custom target distribution (see example above)");
   keys.addFlag("CALC_WORK",false,"calculate the total accumulated work done by the bias since last restart");
   keys.addFlag("WALKERS_MPI",false,"switch on MPI version of multiple walkers");
   keys.addFlag("SERIAL",false,"perform calculations in serial");
diff --git a/src/pytorch/PytorchModel.cpp b/src/pytorch/PytorchModel.cpp
index 7a7775e759..68719163e9 100644
--- a/src/pytorch/PytorchModel.cpp
+++ b/src/pytorch/PytorchModel.cpp
@@ -94,7 +94,6 @@ PLUMED_REGISTER_ACTION(PytorchModel,"PYTORCH_MODEL")
 
 void PytorchModel::registerKeywords(Keywords& keys) {
   Function::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("optional","FILE","Filename of the PyTorch compiled model");
   keys.addOutputComponent("node", "default", "Model outputs");
 }
diff --git a/src/refdist/MatrixProductDiagonal.cpp b/src/refdist/MatrixProductDiagonal.cpp
index e97a0f9c55..54d022b9ff 100644
--- a/src/refdist/MatrixProductDiagonal.cpp
+++ b/src/refdist/MatrixProductDiagonal.cpp
@@ -47,7 +47,8 @@ class MatrixProductDiagonal : public ActionWithVector {
 PLUMED_REGISTER_ACTION(MatrixProductDiagonal,"MATRIX_PRODUCT_DIAGONAL")
 
 void MatrixProductDiagonal::registerKeywords( Keywords& keys ) {
-  ActionWithVector::registerKeywords(keys); keys.use("ARG");
+  ActionWithVector::registerKeywords(keys);
+  keys.addInputKeyword("compulsory","ARG","vector/matrix","the two vectors/matrices whose product are to be taken");
   keys.setValueDescription("scalar/vector","a vector containing the diagonal elements of the matrix that obtaned by multiplying the two input matrices together");
 }
 
diff --git a/src/symfunc/ThreeBodyGFunctions.cpp b/src/symfunc/ThreeBodyGFunctions.cpp
index 9f6b3f52a0..2517513f11 100644
--- a/src/symfunc/ThreeBodyGFunctions.cpp
+++ b/src/symfunc/ThreeBodyGFunctions.cpp
@@ -51,8 +51,9 @@ class ThreeBodyGFunctions : public ActionWithVector {
 PLUMED_REGISTER_ACTION(ThreeBodyGFunctions,"GSYMFUNC_THREEBODY")
 
 void ThreeBodyGFunctions::registerKeywords( Keywords& keys ) {
-  ActionWithVector::registerKeywords( keys ); keys.use("ARG");
-  keys.add("compulsory","WEIGHT","the matrix that contains the weights that should be used for each connection");
+  ActionWithVector::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","matrix","three matrices containing the bond vectors of interest");
+  keys.addInputKeyword("compulsory","WEIGHT","matrix","the matrix that contains the weights that should be used for each connection");
   keys.add("numbered","FUNCTION","the parameters of the function you would like to compute");
   ActionWithValue::useCustomisableComponents( keys );
 }
diff --git a/src/tools/Keywords.cpp b/src/tools/Keywords.cpp
index d409be915a..ca9af95d6e 100644
--- a/src/tools/Keywords.cpp
+++ b/src/tools/Keywords.cpp
@@ -197,6 +197,16 @@ void Keywords::add( const std::string & t, const std::string & k, const std::str
   keys.push_back(k);
 }
 
+void Keywords::addInputKeyword( const std::string & t, const std::string & k, const std::string & ttt, const std::string & d ) {
+  if( exists(k) ) { remove(k); argument_types[k] = ttt; } else { argument_types.insert( std::pair<std::string,std::string>(k,ttt) ); }
+  add( t, k, d );
+}
+
+void Keywords::addInputKeyword( const std::string & t, const std::string & k, const std::string & ttt, const std::string& def, const std::string & d ) {
+  if( exists(k) ) { remove(k); argument_types[k] = ttt; } else { argument_types.insert( std::pair<std::string,std::string>(k,ttt) ); }
+  add( t, k, def, d );
+}
+
 void Keywords::add( const std::string & t, const std::string & k, const std::string &  def, const std::string & d ) {
   plumed_massert( !exists(k) && !reserved(k) &&  (t=="compulsory" || t=="hidden" ), "failing on keyword " + k ); // An optional keyword can't have a default
   types.insert(  std::pair<std::string,KeyType>(k, KeyType(t)) );
@@ -676,10 +686,26 @@ bool Keywords::componentHasCorrectType( const std::string& name, const std::size
     return (ctypes.find(sname)->second.find("vector")!=std::string::npos);
   } else if( rank==2 ) {
     return (ctypes.find(sname)->second.find("matrix")!=std::string::npos);
-  } else plumed_merror("found value without type");
+  }
   return false;
 }
 
+bool Keywords::checkArgumentType( const std::size_t& rank, const bool& hasderiv ) const {
+  for(auto const& x : argument_types ) {
+    if( rank==0 && x.second.find("scalar")!=std::string::npos ) return true;
+    if( hasderiv && x.second.find("grid")!=std::string::npos ) return true;
+    if( rank==1 && x.second.find("vector")!=std::string::npos ) return true;
+    if( rank==2 && x.second.find("matrix")!=std::string::npos ) return true;
+  }
+  plumed_merror("WARNING: type for input argument has not been specified");
+  return false;
+}
+
+std::string Keywords::getArgumentType( const std::string& name ) const {
+  if( argument_types.find(name)==argument_types.end() ) return "";
+  return argument_types.find(name)->second;
+}
+
 std::string Keywords::getOutputComponentFlag( const std::string& name ) const {
   return ckey.find(name)->second;
 }
diff --git a/src/tools/Keywords.h b/src/tools/Keywords.h
index b3319cecdd..efce8b38a0 100644
--- a/src/tools/Keywords.h
+++ b/src/tools/Keywords.h
@@ -76,6 +76,8 @@ class Keywords {
   std::map<std::string,bool> allowmultiple;
 /// The documentation for the keywords
   std::map<std::string,std::string> documentation;
+/// The type for the arguments in this action
+  std::map<std::string,std::string> argument_types;
 /// The default values for the flags (are they on or of)
   std::map<std::string,bool> booldefs;
 /// The default values (if there are default values) for compulsory keywords
@@ -182,6 +184,13 @@ class Keywords {
   bool outputComponentExists( const std::string& name ) const ;
 /// Check that type for component has been documented correctly
   bool componentHasCorrectType( const std::string& name, const std::size_t& rank, const bool& hasderiv ) const ;
+/// Create the documentation for a keyword that reads arguments
+  void addInputKeyword( const std::string & t, const std::string & k, const std::string & ttt, const std::string & d );
+  void addInputKeyword( const std::string & t, const std::string & k, const std::string & ttt, const std::string& def, const std::string & d );
+/// Check the documentation of the argument types
+  bool checkArgumentType( const std::size_t& rank, const bool& hasderiv ) const ;
+/// Get the valid types that can be used as argument for this keyword
+  std::string getArgumentType( const std::string& name ) const ;
 /// Get the flag that forces this component to be calculated
   std::string getOutputComponentFlag( const std::string& name ) const ;
 /// Get the type for this output component
diff --git a/src/valtools/Concatenate.cpp b/src/valtools/Concatenate.cpp
index 66d4d0025d..6bdae1fe06 100644
--- a/src/valtools/Concatenate.cpp
+++ b/src/valtools/Concatenate.cpp
@@ -57,8 +57,9 @@ class Concatenate :
 PLUMED_REGISTER_ACTION(Concatenate,"CONCATENATE")
 
 void Concatenate::registerKeywords( Keywords& keys ) {
-  Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys ); ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
-  keys.add("numbered","MATRIX","specify the matrices that you wish to join together into a single matrix"); keys.reset_style("MATRIX","compulsory");
+  Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys ); ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("optional","ARG","scalar/vector","the values that should be concatenated together to form the output vector");
+  keys.addInputKeyword("numbered","MATRIX","scalar/matrix","specify the matrices that you wish to join together into a single matrix"); keys.reset_style("MATRIX","compulsory");
   keys.setValueDescription("vector/matrix","the concatenated vector/matrix that was constructed from the input values");
 }
 
diff --git a/src/valtools/Flatten.cpp b/src/valtools/Flatten.cpp
index 73da99b208..07f9680d4f 100644
--- a/src/valtools/Flatten.cpp
+++ b/src/valtools/Flatten.cpp
@@ -55,7 +55,8 @@ PLUMED_REGISTER_ACTION(Flatten,"FLATTEN")
 
 void Flatten::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","matrix","the label for the matrix that you would like to flatten to a vector");
   keys.setValueDescription("vector","a vector containing all the elements of the input matrix");
 }
 
diff --git a/src/valtools/SelectComponents.cpp b/src/valtools/SelectComponents.cpp
index 3d6466090f..6a17f2353a 100644
--- a/src/valtools/SelectComponents.cpp
+++ b/src/valtools/SelectComponents.cpp
@@ -48,7 +48,7 @@ PLUMED_REGISTER_ACTION(SelectComponents,"SELECT_COMPONENTS")
 
 void SelectComponents::registerKeywords( Keywords& keys ) {
   ActionShortcut::registerKeywords( keys );
-  keys.add("compulsory","ARG","the argument we are using to build the shortcut");
+  keys.addInputKeyword("compulsory","ARG","vector/matrix","the value from which we are selecting components");
   keys.add("compulsory","COMPONENTS","the components in the input value that you woul like to build a new vector from");
   keys.needsAction("FLATTEN"); keys.needsAction("CONSTANT"); keys.needsAction("SELECT_WITH_MASK");
   keys.setValueDescription("vector","a vector containing the selected components");
diff --git a/src/valtools/SelectWithMask.cpp b/src/valtools/SelectWithMask.cpp
index 4d41b9c66b..83791be848 100644
--- a/src/valtools/SelectWithMask.cpp
+++ b/src/valtools/SelectWithMask.cpp
@@ -62,10 +62,11 @@ PLUMED_REGISTER_ACTION(SelectWithMask,"SELECT_WITH_MASK")
 
 void SelectWithMask::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.use("ARG");
-  keys.add("optional","ROW_MASK","an array with ones in the rows of the matrix that you want to discard");
-  keys.add("optional","COLUMN_MASK","an array with ones in the columns of the matrix that you want to discard");
-  keys.add("compulsory","MASK","an array with ones in the components that you want to discard");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","scalar/vector/matrix","the label for the value upon which you are going to apply the mask");
+  keys.addInputKeyword("optional","ROW_MASK","vector","an array with ones in the rows of the matrix that you want to discard");
+  keys.addInputKeyword("optional","COLUMN_MASK","vector","an array with ones in the columns of the matrix that you want to discard");
+  keys.addInputKeyword("compulsory","MASK","vector/matrix","an array with ones in the components that you want to discard");
   keys.setValueDescription("vector/matrix","a vector/matrix of values that is obtained using a mask to select elements of interest");
 }
 
diff --git a/src/valtools/VStack.cpp b/src/valtools/VStack.cpp
index 99d7574c97..39c09556c7 100644
--- a/src/valtools/VStack.cpp
+++ b/src/valtools/VStack.cpp
@@ -60,7 +60,8 @@ class VStack : public ActionWithMatrix {
 PLUMED_REGISTER_ACTION(VStack,"VSTACK")
 
 void VStack::registerKeywords( Keywords& keys ) {
-  ActionWithMatrix::registerKeywords( keys ); keys.use("ARG");
+  ActionWithMatrix::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","scalar/vector","the values that you would like to stack together to construct the output matrix");
   keys.setValueDescription("matrix","a matrix that contains the input vectors in its columns");
 }
 
diff --git a/src/vatom/ArgsToVatom.cpp b/src/vatom/ArgsToVatom.cpp
index cacbf3283f..8b0087bd02 100644
--- a/src/vatom/ArgsToVatom.cpp
+++ b/src/vatom/ArgsToVatom.cpp
@@ -61,14 +61,14 @@ PLUMED_REGISTER_ACTION(ArgsToVatom,"ARGS2VATOM")
 
 void ArgsToVatom::registerKeywords( Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys ); ActionWithArguments::registerKeywords( keys );
-  keys.add("compulsory","XPOS","the x position of the atom");
-  keys.add("compulsory","YPOS","the y position of the atom");
-  keys.add("compulsory","ZPOS","the z position of the atom");
-  keys.add("compulsory","MASS","the mass of the atom");
-  keys.add("compulsory","CHARGE","the charge of the atom");
-  keys.add("hidden","XBKP","x position to use in case PBC not set when using PHASES");
-  keys.add("hidden","YBKP","y position to use in case PBC not set when using PHASES");
-  keys.add("hidden","ZBKP","z position to use in case PBC not set when using PHASES");
+  keys.addInputKeyword("compulsory","XPOS","scalar","the value to use for the x position of the atom");
+  keys.addInputKeyword("compulsory","YPOS","scalar","the value to use for the y position of the atom");
+  keys.addInputKeyword("compulsory","ZPOS","scalar","the value to use for the z position of the atom");
+  keys.addInputKeyword("compulsory","MASS","scalar","the value to use for the mass of the atom");
+  keys.addInputKeyword("compulsory","CHARGE","scalar","the value to use for the charge of the atom");
+  keys.addInputKeyword("hidden","XBKP","scalar","x position to use in case PBC not set when using PHASES");
+  keys.addInputKeyword("hidden","YBKP","scalar","y position to use in case PBC not set when using PHASES");
+  keys.addInputKeyword("hidden","ZBKP","scalar","z position to use in case PBC not set when using PHASES");
   keys.addFlag("FRACTIONAL",false,"the input arguments are calculated in fractional coordinates so you need to multiply by the cell");
   keys.addOutputComponent("x","default","scalar","the x coordinate of the virtual atom");
   keys.addOutputComponent("y","default","scalar","the y coordinate of the virtual atom");
diff --git a/src/ves/VesDeltaF.cpp b/src/ves/VesDeltaF.cpp
index f0aaeae213..d878d27854 100644
--- a/src/ves/VesDeltaF.cpp
+++ b/src/ves/VesDeltaF.cpp
@@ -180,7 +180,6 @@ PLUMED_REGISTER_ACTION(VesDeltaF,"VES_DELTA_F")
 
 void VesDeltaF::registerKeywords(Keywords& keys) {
   Bias::registerKeywords(keys);
-  keys.use("ARG");
   keys.add("optional","TEMP","temperature is compulsory, but it can be sometimes fetched from the MD engine");
 //local free energies
   keys.add("numbered","FILE_F","names of files containing local free energies and derivatives. "
diff --git a/src/ves/VesLinearExpansion.cpp b/src/ves/VesLinearExpansion.cpp
index fc1e3948ed..8f1ce7f2c1 100644
--- a/src/ves/VesLinearExpansion.cpp
+++ b/src/ves/VesLinearExpansion.cpp
@@ -328,7 +328,6 @@ void VesLinearExpansion::registerKeywords( Keywords& keys ) {
   VesBias::useGridBinKeywords(keys);
   VesBias::useProjectionArgKeywords(keys);
   //
-  keys.use("ARG");
   keys.add("compulsory","BASIS_FUNCTIONS","the label of the one dimensional basis functions that should be used.");
   keys.addOutputComponent("force2","default","scalar","the instantaneous value of the squared force due to this bias potential.");
 }
diff --git a/src/wham/Wham.cpp b/src/wham/Wham.cpp
index 9fa6797e0b..62396f450b 100644
--- a/src/wham/Wham.cpp
+++ b/src/wham/Wham.cpp
@@ -96,8 +96,8 @@ PLUMED_REGISTER_ACTION(Wham,"WHAM")
 
 void Wham::registerKeywords(Keywords& keys ) {
   Action::registerKeywords( keys ); ActionWithValue::registerKeywords( keys );
-  ActionWithArguments::registerKeywords( keys ); keys.remove("ARG");
-  keys.add("compulsory","ARG","the stored values for the bias");
+  ActionWithArguments::registerKeywords( keys );
+  keys.addInputKeyword("compulsory","ARG","scalar/vector/matrix","the stored values for the bias");
   keys.add("compulsory","MAXITER","1000","maximum number of iterations for WHAM algorithm");
   keys.add("compulsory","WHAMTOL","1e-10","threshold for convergence of WHAM algorithm");
   keys.add("optional","TEMP","the system temperature.  This is not required if your MD code passes this quantity to PLUMED");