diff --git a/src/java/org/apache/lucene/index/AbstractAllTermDocs.java b/src/java/org/apache/lucene/index/AbstractAllTermDocs.java
index e3d9094810d..3b0a7132650 100644
--- a/src/java/org/apache/lucene/index/AbstractAllTermDocs.java
+++ b/src/java/org/apache/lucene/index/AbstractAllTermDocs.java
@@ -19,6 +19,13 @@ package org.apache.lucene.index;
 
 import java.io.IOException;
 
+/** Base class for enumerating all but deleted docs.
+ * 
+ * <p>NOTE: this class is meant only to be used internally
+ * by Lucene; it's only public so it can be shared across
+ * packages.  This means the API is freely subject to
+ * change, and, the class could be removed entirely, in any
+ * Lucene release.  Use directly at your own risk! */
 public abstract class AbstractAllTermDocs implements TermDocs {
 
   protected int maxDoc;