//----------REV----------
//case1
G90 G01 X100 Y-500 Z0 F10000
G17  X100 Y-500 I50 J0  REV1  G3

//case2
G01 X250 Y-500 Z0 
G3 X250 Y-500 Z100 I50 J0 REV5

//case3
G01 X400 Z0 
G90 G2 X450 Y-450 I50 J0 Z150 REV5