diff --git a/src/modality-specific-files/magnetoencephalography.md b/src/modality-specific-files/magnetoencephalography.md
index 9548f84ee3..7b1990d198 100644
--- a/src/modality-specific-files/magnetoencephalography.md
+++ b/src/modality-specific-files/magnetoencephalography.md
@@ -74,9 +74,8 @@ For example: `sub-01_task-nback_markers.sqd`
 Please refer to the [MEG File Formats Appendix](../appendices/meg-file-formats.md)
 for general information on how to deal with such manufacturer specifics and to see more examples.
 
-The [`proc-<label>`](../appendices/entities.md#proc) entity is analogous to the
-[`rec-<label>`](../appendices/entities.md#rec) entity for MRI,
-and denotes a variant of a file that was a result of particular processing performed on the device.
+The [`proc-<label>`](../appendices/entities.md#proc) entity
+denotes a variant of a file that was a result of particular processing performed on the device.
 This is useful for files produced in particular by Neuromag/Elekta/MEGIN's MaxFilter
 (for example, sss, tsss, trans, quat, mc),
 which some installations impose to be run on raw data prior to analysis.
diff --git a/src/schema/objects/entities.yaml b/src/schema/objects/entities.yaml
index e26b793c44..8a992ff942 100644
--- a/src/schema/objects/entities.yaml
+++ b/src/schema/objects/entities.yaml
@@ -215,7 +215,7 @@ processing:
   name: proc
   display_name: Processed (on device)
   description: |
-    The proc label is analogous to rec for MR and denotes a variant of
+    The proc label denotes a variant of
     a file that was a result of particular processing performed on the device.
 
     This is useful for files produced in particular by Neuromag/Elekta/MEGIN's
@@ -231,6 +231,8 @@ reconstruction:
   description: |
     The `rec-<label>` entity can be used to distinguish different reconstruction algorithms
     (for example, `MoCo` for the ones using motion correction).
+    Also consider `proc-<label>` entity to represent additional processing performed on the data
+    after initial reconstruction (for example, spatial smoothing).
   type: string
   format: label
 recording:
diff --git a/src/schema/rules/files/raw/anat.yaml b/src/schema/rules/files/raw/anat.yaml
index 54edaccc22..addd0289c0 100644
--- a/src/schema/rules/files/raw/anat.yaml
+++ b/src/schema/rules/files/raw/anat.yaml
@@ -26,6 +26,7 @@ nonparametric:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     part: optional
 
@@ -61,6 +62,7 @@ parametric:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
 
 defacemask:
@@ -79,6 +81,7 @@ defacemask:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     modality: optional
 
@@ -99,6 +102,7 @@ multiecho:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     echo: required
     part: optional
@@ -119,6 +123,7 @@ multiflip:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     echo: optional
     flip: required
@@ -140,6 +145,7 @@ multiinversion:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     inversion: required
     part: optional
@@ -160,6 +166,7 @@ mp2rage:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     echo: optional
     flip: optional
@@ -183,6 +190,7 @@ vfamt:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     echo: optional
     flip: required
@@ -205,6 +213,7 @@ mtr:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     mtransfer: required
     part: optional
diff --git a/src/schema/rules/files/raw/channels.yaml b/src/schema/rules/files/raw/channels.yaml
index 88c8e79aa8..ca0acab2b6 100644
--- a/src/schema/rules/files/raw/channels.yaml
+++ b/src/schema/rules/files/raw/channels.yaml
@@ -8,22 +8,15 @@ channels:
   datatypes:
     - eeg
     - ieeg
+    - meg
     - nirs
   entities:
     subject: required
     session: optional
     task: required
     acquisition: optional
-    run: optional
-
-# MEG has an additional entity available
-channels__meg:
-  $ref: rules.files.raw.channels.channels
-  datatypes:
-    - meg
-  entities:
-    $ref: rules.files.raw.channels.channels.entities
     processing: optional
+    run: optional
 
 coordsystem:
   suffixes:
diff --git a/src/schema/rules/files/raw/dwi.yaml b/src/schema/rules/files/raw/dwi.yaml
index 98840ef6a1..a03cbf68e7 100644
--- a/src/schema/rules/files/raw/dwi.yaml
+++ b/src/schema/rules/files/raw/dwi.yaml
@@ -15,6 +15,7 @@ dwi:
     session: optional
     acquisition: optional
     reconstruction: optional
+    processing: optional
     direction: optional
     run: optional
     part: optional
@@ -33,6 +34,7 @@ sbref:
     session: optional
     acquisition: optional
     reconstruction: optional
+    processing: optional
     direction: optional
     run: optional
     part: optional
diff --git a/src/schema/rules/files/raw/eeg.yaml b/src/schema/rules/files/raw/eeg.yaml
index 676d66dc1b..270bbab17e 100644
--- a/src/schema/rules/files/raw/eeg.yaml
+++ b/src/schema/rules/files/raw/eeg.yaml
@@ -18,4 +18,5 @@ eeg:
     session: optional
     task: required
     acquisition: optional
+    processing: optional
     run: optional
diff --git a/src/schema/rules/files/raw/fmap.yaml b/src/schema/rules/files/raw/fmap.yaml
index 8f5e66a508..f9b27bc289 100644
--- a/src/schema/rules/files/raw/fmap.yaml
+++ b/src/schema/rules/files/raw/fmap.yaml
@@ -53,6 +53,7 @@ TB1DAM:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     flip: required
     inversion: optional
@@ -73,6 +74,7 @@ TB1EPI:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     echo: required
     flip: required
@@ -97,6 +99,7 @@ RFFieldMaps:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     echo: optional
     flip: optional
@@ -118,6 +121,7 @@ TB1SRGE:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
     echo: optional
     flip: required
@@ -140,4 +144,5 @@ parametric:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     run: optional
diff --git a/src/schema/rules/files/raw/func.yaml b/src/schema/rules/files/raw/func.yaml
index 589d187444..226b9d049e 100644
--- a/src/schema/rules/files/raw/func.yaml
+++ b/src/schema/rules/files/raw/func.yaml
@@ -17,6 +17,7 @@ func:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     direction: optional
     run: optional
     echo: optional
@@ -38,6 +39,7 @@ phase:
     acquisition: optional
     ceagent: optional
     reconstruction: optional
+    processing: optional
     direction: optional
     run: optional
     echo: optional
diff --git a/src/schema/rules/files/raw/ieeg.yaml b/src/schema/rules/files/raw/ieeg.yaml
index 587f9bcbb8..ac7b76d77a 100644
--- a/src/schema/rules/files/raw/ieeg.yaml
+++ b/src/schema/rules/files/raw/ieeg.yaml
@@ -19,4 +19,5 @@ ieeg:
     session: optional
     task: required
     acquisition: optional
+    processing: optional
     run: optional
diff --git a/src/schema/rules/files/raw/nirs.yaml b/src/schema/rules/files/raw/nirs.yaml
index 8dfc41e861..5bd7b430fb 100644
--- a/src/schema/rules/files/raw/nirs.yaml
+++ b/src/schema/rules/files/raw/nirs.yaml
@@ -12,4 +12,5 @@ nirs:
     session: optional
     task: required
     acquisition: optional
+    processing: optional
     run: optional
diff --git a/src/schema/rules/files/raw/perf.yaml b/src/schema/rules/files/raw/perf.yaml
index 61cbc24721..b158e5c745 100644
--- a/src/schema/rules/files/raw/perf.yaml
+++ b/src/schema/rules/files/raw/perf.yaml
@@ -14,6 +14,7 @@ asl:
     session: optional
     acquisition: optional
     reconstruction: optional
+    processing: optional
     direction: optional
     run: optional
 
@@ -30,6 +31,7 @@ aslcontext:
     session: optional
     acquisition: optional
     reconstruction: optional
+    processing: optional
     direction: optional
     run: optional
 
@@ -45,4 +47,5 @@ asllabeling:
     session: optional
     acquisition: optional
     reconstruction: optional
+    processing: optional
     run: optional
diff --git a/src/schema/rules/files/raw/pet.yaml b/src/schema/rules/files/raw/pet.yaml
index a94cb9addd..b00e561857 100644
--- a/src/schema/rules/files/raw/pet.yaml
+++ b/src/schema/rules/files/raw/pet.yaml
@@ -14,6 +14,7 @@ pet:
     task: optional
     tracer: optional
     reconstruction: optional
+    processing: optional
     run: optional
 
 blood:
@@ -30,5 +31,6 @@ blood:
     task: optional
     tracer: optional
     reconstruction: optional
+    processing: optional
     run: optional
     recording: required
diff --git a/src/schema/rules/files/raw/task.yaml b/src/schema/rules/files/raw/task.yaml
index 1767814eb9..d8f52ae88b 100644
--- a/src/schema/rules/files/raw/task.yaml
+++ b/src/schema/rules/files/raw/task.yaml
@@ -49,6 +49,7 @@ events__mri:
     $ref: rules.files.raw.task.events.entities
     ceagent: optional
     reconstruction: optional
+    processing: optional
     direction: optional
 
 events__pet:
@@ -62,6 +63,7 @@ events__pet:
     task: required
     tracer: optional
     reconstruction: optional
+    processing: optional
     run: optional
 
 timeseries__mri:
@@ -72,6 +74,7 @@ timeseries__mri:
   entities:
     $ref: rules.files.raw.task.timeseries.entities
     reconstruction: optional
+    processing: optional
     direction: optional
 
 timeseries__func:
@@ -101,5 +104,6 @@ timeseries__pet:
     task: required
     tracer: optional
     reconstruction: optional
+    processing: optional
     run: optional
     recording: optional