APA is an acronym for the phrase "Amateur Press Assocaition", a concept that originated in the 1800s and which has been expanded on ever since. Interregnum is published on paper aprox. eight times a year.

Each issue is made up of "zines", short personal creations (each anywhere from 2-20 pages) written and designed by different authors. Either a master copy or a pile of pre-printed zines are sent to the Editor, who prints from the masters, collates and organizes them. They are then bound together and mailed out to each of the contributing writers, as well as to individual subscribers.

Zines include opinions, articles, reviews, short fiction, artwork, occasional cartoon strips, and commentary/discussions about the zines of other contributors to the APA.

The writers and the subscribers both subsidize the costs for printing and mailing out the issues of the APA, having established an account with the editor. Most APA's are not published for a profit, but to entertain, enlighten and share with the contributors and subscribers.