The root of an Atom Document (i.e., atom:feed in an Atom Feed Document, atom:entry in an Atom Entry Document) MAY be encrypted, using the mechanisms described by XML Encryption Syntax and Processing [W3C.REC-xmlenc-core-20021210].
Many of Atom's elements share a few common structures. This section defines those structures and their requirements for convenient reference by the appropriate element definitions.
When an element is identified as being a particular kind of construct, it inherits the corresponding requirements from that construct's definition in this section.
Note that there MUST NOT be any white space in a Date construct or in any IRI. Some XML-emitting implementations erroneously insert white space around values by default, and such implementations will emit invalid Atom Documents.
The XML Namespaces URI [W3C.REC-xml-names-19990114] for the XML data format described in this specification is:
For convenience, this data format may be referred to as "Atom 1.0". This specification uses "Atom" internally.
The atom content element is designed to support the direct inclusion of other XML vocabularies.
Any fully qualified URI may be used a value for the rel attribute of link elements.
Elements from other namespaces may be included pretty much anywhere. This means that most RSS 1.0 and RSS 2.0 modules may be used in Atom.
In 2004, discussions began about moving the project to a standards body such as the World Wide Web Consortium or the Internet Engineering Task Force (IETF). The group eventually chose the IETF and the Atompub working group was formally set up in June 2004, finally giving the project a charter and process. The Atompub working group is co-chaired by Tim Bray (the co-editor of the XML specification) and Paul Hoffman. Initial development was focused on the syndication format.
When Atom emerged as a format intended to rival or replace RSS, CNET described the motivation of its creators as follows: "Winer's opponents are seeking a new format that would clarify RSS ambiguities, consolidate its multiple versions, expand its capabilities, and fall under the auspices of a traditional standards organization
Web feeds are used by the blogging community to share recent entries' headlines, full text, and even attached multimedia files. These providers allow other websites to incorporate the blog's "syndicated" headline or headline-and-short-summary feeds under various usage agreements. Atom and other web syndication formats are now used for many purposes, including journalism, marketing, bug-reports, or any other activity involving periodic updates or publications.
The name Atom applies to a pair of related standards. The Atom Syndication Format is an XML language used for web feeds, while the Atom Publishing Protocol is a simple HTTP-based protocol for creating and updating web resources.