Folio

Description
Folio is a format that is used by Adobe's Digital Publishing Suite. Its main purpose is to describe and package collections of (magazine) articles. The main XML structure is called the folio manifest. Each article is in turn described using a similar data structure: the assets used to render it, metadata describing the article, and a declarative syntax that represents its interactive contents.

A folio can be packaged in three different ways:

1. fulfillment form - also known as the multifile or partially extracted form. Here, the folio consists of a single folio manifest and a collection of Zip packages, one per article. A folio may also contain an optional bundle HTMLResources, which can be used to collect common resources that are used by multiple articles within the folio (e.g. HTML, CSS).

2.  exploded form - this is the result after unpackaging the fulfillment form to a local file system. The exploded form has a folio manifest file at the root of the local cache directory, with a collection of directories at the same level, where each directory represents one article.

3. packaged form - this is the result of packaging the contents of the exploded form into one ZIP file, preserving all paths.

In 2014 Adobe released the format under a free license.

Specification

 * Folio Format Specification version 2.4 (release 29)

Software

 * Adobe Digital Publishing Suite
 * Adobe Content Viewer (mobile apps for Android and iOS)

Links

 * Adobe to offer .folio format under free license. What’s it mean?
 * Latest DPS stats show rapid growth in circulation and readership; .folio file format to be offered under free license