The bibliographic description for all map serials (5) includes frequency statement following the physical description area and preceding the notes.

The frequency statement is usually a single word, unless the frequency of publication has varied. Variations in the frequency of a serial during its history may be noted either completely or partially depending on the complexity of the resultant statement.

The term irregular is used to denote either no discernible pattern to the periodicity of a publication or an extremely complicated history of changing frequencies. Examples:

See also:

Collective Sets/Series/Serials