adl:formats

The adl:formats bucket contains terms, drawn from an ADL-controlled vocabulary, that indicate the mechanisms by which a copy of the object can be delivered to a library user. In general, a format is the target of an "is-available-as" relationship; i.e., a format can be applied to an object if the assertion "object is available as format" makes sense. The distinction between type and format can be subtle (such as "aerial photograph" is a type, while "9x9 inch monochrome film positive" is a format), which is a further argument in favor of their controlled vocabularies.

Where possible, the controlled vocabulary for the adl:formats bucket exploits standard terminology, such as MIME type specifiers for digital data. These have the advantage of being directly intelligible to programs accessing ADL holdings.

Since digital data can often be trivially and losslessly translated from one format to another, it can make sense to assign multiple formats to a single digital object. On the other hand, an analog object (such as a paper map) is generally cast into a single format upon creation, and can only be re-formatted imperfectly and with substantial effort (such as photographic enlargement.)