Roland G-800 Reference Manual page 15

Tone pages and Tone mode, Tone Edit (Source switch)
Select the part using the [PAGE] A/¥ buttons and select Prf or Sng.
The Part parameter settings remain in effect until you select another Performance
Memory (or until you change them).
In this case, the Realtime Part Parameters are affected by NRPN messages included in
the Standard MIDI File you are playing back. In other words, when set to Sng, Part
Parameter settings will change if the Standard MIDI File contains other settings.
Note that there is little difference between Prf and Sng as long as you don't play back a
Standard MIDI File.
Sng
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