Thanks to David’s (KI6ZHD) reply to my post on the Linpac site, here’s a quick summary on setting up Linpac for unproto frames:
:unsrc yourcall
:undest "Yourname node1 node2 node-etc"
where node1 etc is your digipeater node list for routing your unproto packets between nodes that can hear each other.
:unproto the message
sends an unproto frame with the text specfied.
You can also open the F10 window and all text typed there gets sent as unproto frames.
unsrc and undest can be defined in the ~/Linpac/macros/init.mac file.