G21 G90
(Source basis: LinuxCNC src/emc/rs274ngc/interp_check.cc check_g_codes only treats P-1.0 as missing for G4.)
(Source basis: src/emc/rs274ngc/interp_convert.cc convert_dwell passes other P values to DWELL unchanged.)
G4 P-1.001
G4 P-0.9999
G4 P-2 P3