diff -r 78e4080252be -r 62afd820d3ae web/form.py
--- a/web/form.py	Fri Mar 27 17:08:27 2009 +0100
+++ b/web/form.py	Fri Mar 27 17:09:43 2009 +0100
@@ -220,13 +220,13 @@
         self.context = None
 
     @iclassmethod
-    def field_by_name(cls_or_self, name):
+    def field_by_name(cls_or_self, name, role='subject'):
         if isinstance(cls_or_self, type):
             fields = cls_or_self._fields_
         else:
             fields = cls_or_self.fields
         for field in fields:
-            if field.name == name:
+            if field.name == name and field.role == role:
                 return field
         raise Exception('field %s not found' % name)
     
@@ -309,7 +309,7 @@
     def form_field_id(self, field):
         return field.id
    
-    def form_field_vocabulary(self, field):
+    def form_field_vocabulary(self, field, limit=None):
         raise NotImplementedError
 
     def form_buttons(self):