Index: docs/en/mapfile/layer.txt
===================================================================
--- docs/en/mapfile/layer.txt	(revision 12908)
+++ docs/en/mapfile/layer.txt	(working copy)
@@ -876,8 +876,9 @@
    pair: LAYER; UNITS
     
 UNITS [feet|inches|kilometers|meters|miles|nauticalmiles|dd|pixels|percentages]
-    Units of the layer. `Percentages` was added in MapServer 4.10 and is mostly
-    geared for inline features. `Nauticalmiles` was added in MapServer 5.6.
+    Units of the layer. `Percentages`, in this case a value between 0 and 1,
+    was added in MapServer 4.10 and is mostly geared for inline features. 
+    `Nauticalmiles` was added in MapServer 5.6.
 
 .. index::
    pair: VALIDATION; LAYER