G97 is the cancellation of constant cutting speed and storing of final speed set point of G96 i.e. after programming G97, the speed at which the spindle was running (when working under constant surface speed) is retained as the constant spindle speed.
N5 G96 S250 ;
N10 G01 X26.Z5.F0.21 ;
N15 Z-25. ;
N20 X30. ;
N25 G00 Z5. ;
N30 G97 ;
N5 – constant cutting speed 250 m/min.
N30 – G97 cancels G96. Spindle speed correspondence to X30 (2650 rpm) is retained.
No other information is programmed in this block.