Document modification check by content.

diff --git a/src b/src
index c5b2da3a5293c824a0d29d32fe1e6e5afc8d25fc..719f6c8b4ec0c27ee008bcacd92ff8d4c60157ff 100755 (executable)
--- a/src
+++ b/src
@@ -557,6 +557,10 @@ A - The file has been registered into SRC but has no commits.
 
 L - The file is locked.
 
+Modification status is by content (using a SHA1 hash) rather than date.
+Thus, if you make changes to a work file in your editor, then undo
+them, the file's status returns to '='.
+
 You can usually recover of file from A, L, and ! status with src
 checkout.  A and L statuses should only occur if you have used RCS
 directly on a file, or if you have called 'src add' manually.