Sorry, Im always missreading things :( ... you said that -1 , -2 .. refer to previous lines in the file, I'd personally take a guess at them refering to the last vt entry.. I mean -2 means the second from last vt entry(rather than file line) , -n being the nth from last vt etc... maybe you can apply negatives to the v coords as well, although ( I hope not :( ). Barrie