xbiff(1) on Linux
The text edd9d5d17d6b, as Debian 6.0 (Squeeze) shipped it.
mailbox flag for X
Flags it lists
-
-bd -
-bg -
-bw -
-display -
-fg -
-file -
-geometry -
-help -
-rv -
-shape -
-update -
-volume -
-xrm