Custom prosigns can be sent using + in the CLI or in memories as a macro. Several “hard wired” / common prosigns are available for various keys on the PS2 keyboard like =, -, &, etc. and the Sroll Lock key can be used to create custom prosigns on the fly.
If you are programming a memory in command mode using the paddle, the + macro can be used to create prosigns. The \ is six dahs ( – – – – – – ) and + is didahdidahdit ( . – . – . ). Common prosigns AR, BK, and SK are automatically recognized and do not need to be proceeded with a + macro, just send the prosign as you normally would (AR would be didahdidahdit, not didah didahdit).