Excellent - worked like a charm! Unicode had crossed my mind (since it was introduced in 5.8.0, bugs in it seemed likely, plus it would explain why the bytes consumed varied from record to record), but I didn't see anything in the hex dumps of the data which looked likely to trigger interpretation as unicode.

I'll have to remember that :raw... I've heard about 3-argument open as a security measure (to protect from user-entered filenames starting with ">", etc.), but this is the first time I've seen it used for anything more than that.

Thanks again!