I did a quick test toggling the "Sh" box and the "Tx6" box.

I guess that "Sh" stands for 'Shorthand', as in the Shorthand messaging used in other modes?

So, clicking on "Sh" changes Tx4 to "@1500(RRRR) which I guess means it's going to transmit the shorthand message "RRR" at 1500Hz audio offset? It also sets Tx5 to @1750 (73) and Tx6 to @1000 (Tune).

Clicking on the Tx6 box changed the Tx6 option to @1250 (SEND MSGS), I'm not sure what will do?  Will it just send "SEND MSGS" on 1250Hz audio offset?  What will that mean or do?  I guess we will have to wait for the full explanation in the updated manual.

If I am correct about the @X frequencies being the audio frequency used to send the various texts in the brackets, then people are going to need to know because, at present, the testing I've seen going on has been audio frequency specific.  So, someone is, say, using 600Hz, someone else, say, 1000Hz, another on 1500Hz and so on up the audio bandwidth. If stations suddenly start using these Sh options, and if I'm right about what the @X means, then it is going to start causing a bit of confusion, I think...

Cheers - Dave (G0DJA)