Issue frequencies are related to how often continuing resources (eg periodicals, magazines etc) are issued. Our issue frequency vocabulary list is sourced from the US Library of Congress, MARC Standards Office, MARC Frequency of Issue Term List, and other, more detailed explanatory material (eg MARC 21 Format for Bibliographic Data 008 – Continuing Resources (NR)).

It should be noted that we have not implemented the related Regularity term list (the intended regularity of an item).