diff --git a/tren.py b/tren.py
index 7c91d86..7d05e50 100755
--- a/tren.py
+++ b/tren.py
@@ -8,7 +8,7 @@
 PROGNAME = "tren.py"
 BASENAME = PROGNAME.split(".py")[0]
 PROGENV  = BASENAME.upper()
-RCSID = "$Id: tren.py,v 1.171 2010/03/06 15:57:21 tundra Exp $"
+RCSID = "$Id: tren.py,v 1.172 2010/03/06 16:26:17 tundra Exp $"
 VERSION = RCSID.split()[2]
 
 # Copyright Information
@@ -39,6 +39,8 @@
 
 import copy
 import getopt
+import grp
+import pwd
 import os
 import re
 from   stat import *
@@ -107,8 +109,12 @@
 TOKCMDEXEC =  "`"             # Delimiter for command execution renaming tokens
 TOKDELIM   =  "/"             # Delimiter for all renaming tokens
 TOKENV     =  "$"             # Introducer for environment variable replacement tokens
+TOKFILGID  =  "g"             # File GID replacement token
+TOKFILGRP  =  "G"             # File Group Name replacement token
 TOKFILLEN  =  "L"             # File Length replacement token
 TOKFILNAM  =  "F"             # File Name replacement token
+TOKFILUID  =  "u"             # File UID replacement token
+TOKFILUNAM =  "U"             # File User Name replacement token
 
 
 # Internal program state literals
@@ -719,11 +725,23 @@
             # File Attribute Renaming Tokens
             ###
 
-            if r[2] == TOKFILLEN:
+            if r[2] == TOKFILGID:
+                r[2] = str(self.RenNames[target][STATS][ST_GID])
+
+            elif r[2] == TOKFILGRP:
+                r[2] = grp.getgrgid(self.RenNames[target][STATS][ST_GID])[0]
+
+            elif r[2] == TOKFILLEN:
                 r[2] = str(self.RenNames[target][STATS][ST_SIZE])
 
             elif r[2] == TOKFILNAM:
                 r[2] = os.path.basename(target)
+
+            elif r[2] == TOKFILUID:
+                r[2] = str(self.RenNames[target][STATS][ST_UID])
+
+            elif r[2] == TOKFILUNAM:
+                r[2] = pwd.getpwuid(self.RenNames[target][STATS][ST_UID])[0]
                 
 
             ###
@@ -741,7 +759,7 @@
 
                 command = r[2][1:-1]
 
-                # Handle Windows variants which act differently
+                # Handle Windows variants - they act differently
 
                 if os.name != 'posix':
                     pipe = os.popen(command, 'r')