diff --git a/base_classes/NXdata.nxdl.xml b/base_classes/NXdata.nxdl.xml
index 5be1866318..6b5f86f9f7 100644
--- a/base_classes/NXdata.nxdl.xml
+++ b/base_classes/NXdata.nxdl.xml
@@ -70,10 +70,8 @@
 			
 			Declares which NeXus field is the default. 
 			The value is the name of the NeXus field to be plotted.
-			A field of this name *must* exist (either as a NeXus field 
-			or as a link to a NeXus field).
-			The value must match the :ref:`regular expression pattern for NXDL
-			group and field names <validItemName>`.
+			(The value :ref:`names <validItemName>` an existing child
+			of this group. The child group must itself be a NeXus group.)
 			
 			It is recommended (as of NIAC2014) to use this attribute
 			rather than adding a signal attribute to the field.