There's times when force-fitting to an old
catalogue numbering system is practical, one can add -bis numbers, additional commentary such as "this issue, in the
Spain section of the
catalogue, should more correctly be placed in
Gaul alongside issue xyz", or "this issue, previously assigned to
Augustus, is now believed to have been struck under Gaius", you can simply delete numbers for non-existence coins, or modify incorrect descriptions whilst keeping the same number. The extent to which you can correct, whilst staying within the same framework, really depends on the excellence of the original arrangement. Really excellent arrangements are made to stand the test of time, such as Fulvio Orsini's 1557 arrangement of
Roman Republican coins, adopted by many authors, most notably
Babelon in the 19th century, whose numbering system is
still used unchanged today (with the addition of -a -b -c suffixes and deletion of unproved entries) in the
Seaby /
Sear Roman Silver Coins volume 1. The
Cohen arrangement used for
RSC 2 onwards is frankly less successful because it ignores easily available dating information and separates issues which belong together due to accidental quirks of lettering (
Babelon avoids this pedantry). So while you'll see
Babelon numbers in today's
auction descriptions, you are less likely to see
Cohen. I
had no problem adapting the
Crawford arrangement for the RBW book, with the addition of
plenty of footnotes and infill numbers. Sometimes, however, as
Sutherland makes clear, enough is enough, the old arrangement foundations are disintegrating, and you just have to start from scratch, or else be faced with a
catalogue where every second entry is either a new coin
type or demands a footnote explaining why the old arrangement is broke. In the case of
RIC 1, the old arrangement was apparently so broke that a concordance could not be provided. A basic rule of coin cataloguing seems to have been misplaced by
Mattingly and
Sydenham. That rule is to always cite one actual public
collection or public
auction example of each coin
type. That way, when catalogues get revised, concordances can always be made because the coin or its picture can always be re-examined and assigned a new-system number.