Nominal number
Nominal numbers or categorical numbers are numeric codes, meaning numerical*66881242756 used for identification only. The numerical value*66879252052 is in principle irrelevant, and they do not indicate quantity, rank, or any other measurement.
Definition
The term "nominal number" is quite recent and of limited use. It appears to have originated as a usage in school textbooks derived from the statistical term "nominal data", defined as data indicating "...merely statements of qualitative category of membership." This usage comes from the sense of nominal as "name".
Mathematically, nominal numbering is a one-to-one and onto function from a set of objects being named to a set of numerals, which may change (typically growing) over time: it is a function because each object is assigned a single numeral, it is one-to-one because different objects are assigned different numerals, and it is onto because every numeral in the set at a given time has associated with it a single named object.