They totally screwed up that manual. Those lines you're quoting about the notepad are flat out errors. It's clear they copied that stuff directly from the SH3 manual and it doesn't apply to SH4. There is no notepad or x button...
In SH4 if you click the send button it's like ordering "Mark".
I posted my suggestion for how to use the TDC without turning on the PK in the attack tactics thread:
http://www.subsim.com/radioroom/show...&postcount=134