I got the following script for FeedHold, and as a result of the experiment, it succeeded.

In addition to feed hold, please tell me the functions such as Start and Stop that I want to assign to the keyboard.

if mc.mcSignalGetState (mc.mcSignalGetHandle (inst, mc.ISIG_INPUT63)) == 1 then mc.mcCntlFeedHold (inst)
else else
--Do something else
end