=== modified file '__init__.py'
--- __init__.py	2009-04-06 22:40:14 +0000
+++ __init__.py	2010-10-01 17:31:51 +0000
@@ -262,10 +262,13 @@
         return ""
 
 
-def compress_keywords(s):
+def compress_keywords(s, keyword_dicts):
     """Replace cooked style keywords with raw style in a string.
     
+    Note: If the keyword is not known, the text is not modified.
+    
     :param s: the string
+    :param keyword_dicts: an iterable of keyword dictionaries.
     :return: the string with keywords compressed
     """
     _raw_style = _keyword_style_registry.get('raw')
@@ -277,6 +280,11 @@
             break
         result += rest[:match.start()]
         keyword = match.group(1)
+        expansion = _get_from_dicts(keyword_dicts, keyword)
+        if expansion is None:
+            # Unknown expansion - leave as is
+            result += match.group(0)
+        else:
         result += _raw_style % {'name': keyword}
         rest = rest[match.end():]
     return result + rest
@@ -351,7 +359,7 @@
 def _kw_compressor(chunks, context=None):
     """Filter that replaces keywords with their compressed form."""
     text = ''.join(chunks)
-    return [compress_keywords(text)]
+    return [compress_keywords(text, [keyword_registry])]
 
 
 def _kw_expander(chunks, context, encoder=None):

=== modified file 'tests/test_conversion.py'
--- tests/test_conversion.py	2008-07-27 13:04:54 +0000
+++ tests/test_conversion.py	2010-10-01 17:31:51 +0000
@@ -34,6 +34,7 @@
     ('$Foo$$Bar$',      '$Foo: FOO! $$Bar: bar $'),
     ('abc $Foo$ xyz $Bar$ qwe', 'abc $Foo: FOO! $ xyz $Bar: bar $ qwe'),
     ('$Unknown$$Bar$',  '$Unknown$$Bar: bar $'),
+    ('$Unknown: unkn $$Bar$',  '$Unknown: unkn $$Bar: bar $'),
     ('$Foo$$Unknown$',  '$Foo: FOO! $$Unknown$'),
     ('$CallMe$',        '$CallMe: now! $'),
     ]
@@ -44,7 +45,7 @@
     def test_compression(self):
         # Test keyword expansion
         for raw, cooked in _samples:
-            self.assertEqual(raw, compress_keywords(cooked))
+            self.assertEqual(raw, compress_keywords(cooked, [_keywords]))
 
     def test_expansion(self):
         # Test keyword expansion