a penstocker for an automatic drafting machine in which a shutter 15 is slidably mounted on a peripheral wall 13b of the penstocker &# 39 ; s main body 10 such that a desired one or more slits 20 , 21 and 22 , formed on the peripheral wall 13b , are shielded thereby forming a predetermined pattern indicative of a presence or absence of the penstocker main body , a type of pen held by the penstocker main body and an origin of the penstocker main body .