mdconfig(8) on FreeBSD
The text ba09d8580faa, as FreeBSD 12.1-RELEASE shipped it.
create and control memory disks
Flags it lists
-
-L -
-S -
-a -
-d -
-f -
-l -
-n -
-o -
-r -
-s -
-t -
-u -
-x -
-y