Yamaha TG500 Owner's Manual page 145

RS (Pitch EG rate scaling)
Range: -7 ... +7
Allows the overall pitch envelope generator rate for the selected element to
be varied across the entire pitch range.
Plus ("+") settings produce a longer overall envelope time for the low notes
and a shorter envelope time for the high notes. The maximum "+7" setting
produces the greatest envelope length variation across the pitch range. Minus
("–") settings produce the opposite effect — a shorter low-note envelope and
longer high-note envelope. A setting of "+0" results in no envelope length
variation.
VOICE EDIT MODE / 3: Full Edit. 3-4: PEG
3-4-01: LEVEL / 3-4-02: RATE 133