Index: roundup/hyperdb.py
===================================================================
--- roundup/hyperdb.py	(revision 4212)
+++ roundup/hyperdb.py	(working copy)
@@ -37,6 +37,7 @@
     """A roundup property type."""
     def __init__(self, required=False):
         self.required = required
+        self.quiet = False
     def __repr__(self):
         ' more useful for dumps '
         return '<%s.%s>'%(self.__class__.__module__, self.__class__.__name__)
Index: roundup/roundupdb.py
===================================================================
--- roundup/roundupdb.py	(revision 4212)
+++ roundup/roundupdb.py	(working copy)
@@ -561,6 +561,9 @@
                 value.sort()
                 value = ', '.join(value)
             else:
+                # Omit quiet properties from history/changelog
+                if prop.quiet:
+                    continue
                 value = str(value)
                 if '\n' in value:
                     value = '\n'+self.indentChangeNoteValue(value)
@@ -654,6 +657,9 @@
                     l.sort()
                     change += ' -%s'%(', '.join(l))
             else:
+                # Omit quiet properties from history/changelog
+                if prop.quiet:
+                    continue
                 change = '%s -> %s'%(oldvalue, value)
                 if '\n' in change:
                     value = self.indentChangeNoteValue(str(value))
Index: roundup/cgi/templating.py
===================================================================
--- roundup/cgi/templating.py	(revision 4212)
+++ roundup/cgi/templating.py	(working copy)
@@ -1035,6 +1035,10 @@
                                 cell[-1] += ' -> %s'%current[k]
                                 current[k] = old
 
+                    # Omit quiet properties from history/changelog
+                    elif prop.quiet:
+                        continue
+
                     elif isinstance(prop, hyperdb.Date) and args[k]:
                         if args[k] is None:
                             d = ''
Index: roundup/backends/rdbms_common.py
===================================================================
--- roundup/backends/rdbms_common.py	(revision 4212)
+++ roundup/backends/rdbms_common.py	(working copy)
@@ -1639,6 +1639,9 @@
         # for the Database layer to do its stuff
         multilink_changes = {}
 
+        # omit quiet properties from history/changelog
+        quiet_props = []
+
         for propname, value in propvalues.items():
             # check to make sure we're not duplicating an existing key
             if propname == self.key and node[propname] != value:
@@ -1803,6 +1806,9 @@
                     int(value)
                 except ValueError:
                     raise TypeError, 'new property "%s" not boolean'%propname
+            # record quiet properties to omit from history/changelog
+            if prop.quiet:
+                quiet_props.append(propname)
 
         # nothing to do?
         if not propvalues:
@@ -1823,6 +1829,11 @@
         if self.do_journal:
             self.db.addjournal(self.classname, nodeid, ''"set", journalvalues)
 
+        # remove quiet properties from output
+        for propname in quiet_props:
+            if propname in propvalues:
+                del propvalues[propname]
+
         return propvalues
 
     def retire(self, nodeid):