https://gitlab.synchro.net/main/sbbs/-/issues/615#note_3899
According to
http://www.columbia.edu/kermit/ftp/protocol/kuser.pdf Ctrl-X is supposed to work to cancel a file transfer, but maybe that's an actual key-press check (and a character received via comm link).> If you notice a file being sent which you do not really want to send, you may cancel the operation immediately by typing either Control-X or Control-Z. If your are sending a file group, Control-X will cause the current file to be skipped, and Kermit will go on to the next file, whereas Control-Z will cancel sending the entire group and return you to Kermit-20 command level.
--- SBBSecho 3.20-Linux
* Origin: Vertrauen - [vert/cvs/bbs].synchro.net (1:103/705)