PA-AF specifies the following: a metadata format to describe the original structure of digital files archived in a PA-AF file; a metadata format to describe context information related to a PA-AF file and digital files archived in it; a metadata format to describe necessary information to reverse the pre-processing processes applied to digital files prior to archiving them in a PA-AF file; and a file format for carriage of the metadata formats and digital files.
While a general archival process may include processes ranging from creation, delivery to the archival system, to dissemination to consumers, PA-AF is limited in scope as follows. PA-AF specifies neither how to create input content nor any agreement on how the content should be handled and delivered to the archiving process. PA-AF assumes that input content for the archiving process is available in an appropriate digital format. PA-AF specifies the format of a digital archive produced by the archival process. It does not specify how the archive output by the archival process is disseminated to end-users.
Note that the archiving policy and agreements are not included in the scope of PA-AF. PA-AF is independent from any kind of compression scheme or any kind of metadata format. PA-AF provides a mechanism for identifying the pre-processing tools applied to the archived content files. Any kind of compression tool or encryption tool can be specified as an external pre-processing tool. In addition, though PA-AF optionally provides a predefined minimum set of descriptive metadata for its archived contents, any kind of application- specific meta-information can be stored in the PA-AF package as a content file or files if the archive's policy or agreements require it. For this purpose, PA-AF provides a mechanism for linking that meta-information to the archived content file.
In the second edition, the maximum number of files that can be packed in a PA-AF file is extended to more than 65535. The latest reference software and conformance bitstreams are also included.