Index: trunk/lib/Text/FormBuilder/grammar
===================================================================
--- trunk/lib/Text/FormBuilder/grammar	(revision 50)
+++ trunk/lib/Text/FormBuilder/grammar	(revision 55)
@@ -191,5 +191,9 @@
 hint: '[' /[^\]]+/ ']'    { $item[2] }
 
-type: ':' /textarea|text|password|file|checkbox|radio|select|hidden|static/
+# TODO: differentiate between builtins and custom field groups
+type: ':' ( builtin_field | var_name { warn "[Text::FormBuilder] Using field group names directly is not (yet) supported (input line $thisline)\n"; 'text' } )
+
+builtin_field: /textarea|text|password|file|checkbox|radio|select|hidden|static/
+
 
 default: '=' (simple_multiword | quoted_string) { $item[2] }