Punter protocol notes

Testing Punter protocol to download files, from Afterlife BBS.

Logging into BBS, then select the D option (D for Download), then selecting 1 (the first file available for download). After receiving the message "START DOWNLOAD", do the following (it works also typing it "by hand"):

RECEIVER(c64) SENDER(bbs)
------------- -----------

= these first two interactions are not documented =
ACK
              GOO

= here starts the sequence described here https://tinyurl.com/y3kpgpcs =
GOO
              ACK
S/B
              [filetype packet, maybe 4bytes]

This also has an effect, but still don't know what extactly is:

RECEIVER(c64) SENDER(bbs)
------------- -----------
GOO
              GOO
S/B
              ACK
...???...