How do GPO's portamento controls (CC#20 and maybe some I missed) related to the MIDI-defined portamento controls (CC#s 5, 37, 65, 84)? Is the use of these controls the same for both "Standard" and "Notation" instruments? I'd like to hear the the Notation instruments conform with the MIDI standard control definitions, but I'm not holding my breath.)

The doc says CC#20 is active only "... in conjunction with legato playing when the sustain pedal controller is active." In Notation instruments, this would be in conjunction with CC#68 instead of CC#64?

And what does "Hidden" (e.g., Hidden Portamento, Hidden Trills) imply in some of the GPO controls?