Adding to your collection
Looking at the catalogue
An issue is a set of one or more stamps put out or sold as a
group. An issue can range from a single stamp commemorating an
anniversary, up to a long-running definitive series including
dozens of types appearing over a period of years.
Most of the time, an "issue" is easily defined; the issuing authority puts out a press release announcing the issue, supplying the date, and details of the stamps belonging to the issue.
In other cases, things are not so clearcut. The issuer does not make any announcement; the stamps appear at post offices unheralded, or there is a color change with no explanation. In these cases, issue membership is based on tradition or convenience.
It should be noted that the defining characteristic of an issue is purpose, which may or may not be apparent in the design of the stamps in the issue. For instance, a memorial issue for a deceased notable may simply depict the individual at various stages of life, with no explicit mention of the demise.
In StampData, the name of an issue is a short bit of text labelling the issue, such as "Olympics 1964" or "Simplon opening 100th". Each issue by an issuer must have a distinct name, and all stamps belonging to the issue will be listed together in the catalog.
If an issue has a name by which it is most commonly known, that should be its name. If the issuer publishes an official name for the issuer, that should be preferred. If a name is ambiguous, suffixes may be needed; for instance, many countries have a "Christmas" issue every year, and in StampData the issues are disambiguated with the year, as in "Christmas 1994". Issue names should be brief, but need not have the words abbreviated.
For many definitive series, the name of the issue is simply the year in which it was issued.