With much reading and practice I have become a bit familiar with writing autolisp routines. Things I couln't do a year ago are now becoming quitesimple. One thing, however I'm having trouble with is using "while" for loops. Can anyone explain the "while" function and how it works, maybe with a couple of examples. I'm especially baffled by how it is used to read down a data list, looking for info. Any help would be appreciated.