CR vs CNT

CR is the Corner Region option, which is a paid option.

It is used to round off corners, the argument is the radius in mm that the corner will be rounded off by.

They used to call that option accupath, but I think it goes by another name these days. It should round of the corner at the specified radius, but also note that it should be regardless of speed, unlike cnt, which will change if you go messing with the speeds.