Hey g00r00,
I noticed that the linux versions of a40 are packaged with a version of rar that appears to either be too new _or_ the non-free version to unarchive.
This may be of particular interest to you considering that the default unarchive command that ships with mystic will thusly not be able to unrar the new builds :) So...people with Mystic boards probably don't have the nice file_id.diz display in their file listings.
Simple fix, with debian at least, is to 'apt install unrar-nonfree' and then change the archive commands to use 'unrar' instead of 'rar e' or whatever it was.
--- Mystic BBS v1.12 A39 2018/04/21 (Windows/32)
* Origin: Black Flag <ACiD Telnet HQ> blackflagbbs.com (21:1/112)