G98, G99: Z-level Return Mode in Canned Cycles

G98 – return to the position in which the axis was before a series of one or more canned cycles began.

G99 – return to the position defined by the canned cycle parameter R.

When the G98 command is issued, the canned cycle will use the Z position before the beginning of the canned cycle as the return level if this value is greater than the parameter R. Otherwise, the parameter R.

G98 mode is reset when exiting a canned cycle, explicit (G80) or implicit (any other move command). Switching between different canned cycles does not reset the G98 mode. In a series of canned cycles, you can switch between modes G98 and G99.