1 files changed, 5 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 94104ef535c..81768849a4b 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -6095,6 +6095,11 @@ and is the visited file's modification time, as of that time.  If the
 modification time of the most recent save is different, this entry is
 obsolete.
 
+An entry (t . 0) means means the buffer was previously unmodified but
+its time stamp was unknown because it was not associated with a file.
+An entry (t . -1) is similar, except that it means the buffer's visited
+file did not exist.
+
 An entry (nil PROPERTY VALUE BEG . END) indicates that a text property
 was modified between BEG and END.  PROPERTY is the property name,
 and VALUE is the old value.