Movable Type allows you to select multiple types of archiving, however when linking to an archived entry — for example using MTEntryPermalink with no archive_type attribute — or when using MTArchiveList (again, with no archive_type attribute) in your master archive index, the system needs to know which type of archive to link to. You can think of this as your default archiving type.

You can only choose from Archive Types which are enabled for the weblog (see Archive Mapping); if you have not enabled any Archive Types, then "No Archives" will become your Preferred Archive Type by default (i.e., no other choices will be available).