ftp(1) on OpenBSD
The text be15dbdd8f19, as OpenBSD 6.7 shipped it.
Internet file transfer program
Flags it lists
-
-4 -
-6 -
-A -
-C -
-D -
-E -
-M -
-N -
-P -
-S -
-U -
-V -
-a -
-c -
-d -
-e -
-g -
-i -
-k -
-m -
-n -
-o -
-p -
-r -
-s -
-t -
-v -
-w