▁G - code . ▁In ▁ 1 9 8 5 ▁IP C ▁published ▁a ▁generic ▁standard ▁NC ▁format , ▁IP C - NC - 3 4 9 . ▁Later ▁X NC ▁was ▁designed , ▁a ▁simple ▁strict ▁subset ▁of ▁IP C - NC - 3 4 9 , ▁designed ▁not ▁for ▁driving ▁machines ▁but ▁for ▁ex ch anging ▁dr ill ▁information ▁between ▁C AD ▁and ▁C AM . ▁They ▁are ▁collect ively ▁referred ▁to ▁as ▁( PC B ) ▁NC ▁files . ▁ ▁The ▁NC ▁files ▁are ▁primarily ▁used ▁to ▁drive ▁C NC ▁machines , ▁and ▁they ▁are ▁ade qu ate ▁for ▁that ▁task . ▁▁ ▁They ▁are ▁also ▁used ▁to ▁exchange ▁design ▁information ▁between ▁C AD ▁and ▁C AM , ▁for ▁which ▁they ▁are ▁not ▁ade qu ate : ▁essential ▁information ▁such ▁as ▁pl ating ▁and ▁dr ill ▁span ▁is ▁missing . ▁Furthermore , ▁the ▁NC ▁output ▁in ▁C AD ▁systems ▁is ▁often ▁poor ly ▁implemented , ▁resulting ▁in ▁poor ▁registration ▁between ▁dr ill ▁holes ▁and ▁co pper ▁layers ▁and ▁other ▁problems . ▁To ▁exchange ▁date ▁between ▁C AD ▁and ▁C AM ▁it ▁is ▁more ▁preferred ▁to ▁use ▁the ▁Ger ber ▁format . ▁The ▁quality ▁of ▁the ▁Ger ber ▁file ▁output ▁software ▁is ▁typically ▁good , ▁and ▁Ger ber ▁supports ▁attributes ▁to ▁transfer ▁meta - information ▁such ▁as ▁pl ating ▁and ▁span . ▁ ▁IP C - NC - 3 4 9 ▁format ▁ ▁The ▁IP C - NC - 3 4 9 ▁format ▁is ▁the ▁only ▁IP C ▁standard ▁gover ning