I posted this question in General Questions on 29th March, and in New Users on 20th May - no reply from either as yet. It usrely is a basic question for some of the MVP boffins in here: Surely ... someone MUST know the answer?? Here we go: If binary is more efficient speed and space-wise, why isn't it the default format (or read "the best way to save a file)? I'm trying to find out what the downside is before I save a majorly important, large file with heaps of macros in binary and start moving on with it to find a little way down the track I've made a terrible mistake! If it isn't the default there must be a reason - a down side - but I can't find anything in Help to tell me. Anyone know?