----------------------------Original message---------------------------- Since, as Mary says, you use "r" when it is a reprint, use "m" when it has more than one applicable date. "m" does not necessarily mean a span of years, like in a set. Although the dates and the date code usually reflect the 260 $c field, they can reflect a variation shown in the 260 compared with a 500. LC also applies the use of the "r" designation more liberally than would I. They use it on some materials which are only re-issues of the same thing, but count it as a reprint. I have seen this with books, but not enough maps from them that any conclusion can be drawn. But then I learned cataloging from someone who took picune to an art form. Debbie Lords [log in to unmask]