I need to use Excel to maintain a list of a particular part. These parts are
ideally used as pairs. Each part has a class number. In order to use them
as pairs, the class numbers must be within +/- 1 (i.e., a class 5 can be
paired with class 4 or 6).

There are two primary part numbers but as long as the classes are within the
limit, it does not matter. Each part is also serialized, but same rule
applies. However, I must be able to maintain the part number, serial number,
and location for each item (so doing a A-Z sort doesn't really help).