XOXO is also a symbol for Hugs and Kisses.

XOXO (Extensible Open XHTML Outlines) is an XML format for outlines built from XHTML modularization. Developed by several authors as an attempt to reuse XHTML building blocks instead of inventing unnecessary new XML elements/attributes, XOXO is both based on existing behavior of publishing outlines, lists, and blogrolls on the Web, and as a general outline format for 1:1 processing of fundamental programming language datastructures.

The XOXO specification defines an outline as a hierarchical, ordered list of arbitrary elements. The specification is fairly open which makes it suitable for many types of list data. E.g. the more semantic version of the S5 presentation file format is based upon XOXO.

XML format

The XML elements in a XOXO document are:

<ol class="xoxo"> and <ul class="xoxo"> : The ordered list and unordered list are the root elements of XOXO. They may contain the class attribute with the value "xoxo". They are also used as containers for outline items. They may have the attribute compact="compact" to indicate state of whether child items are visible or not.

<li> : Represents an item in the outline. May contain an ordered list or unordered list element to contain child items which themselves may do so as well.

<a> : Represents a hyperlink for an item in the outline. May have a "title" attribute to indicate additional information, a "type" attribute to indicate the MIME type of the resource at the destination of the href, a "rel" attribute to indicate the relationship of the resource at the href to this outline (e.g. using XFN), and/or a "rev" attribute to indicate the relationship of this outline to the resource at the href (e.g. using VoteLinks).

<dl> : May contain any number of arbitrary properties using <dt> (definition term) and <dd> (definition) elements.

Example XOXO uses

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• play list
• specification
• presentation
• directory
• blogroll

See also

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• XHTML
• microformats
• XFN
• VoteLinks
• OML
• OPML
• S5 file format

External links

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• XOXO specification
• xoxo.py Open source Python library for XOXO outlines
• outliner.js Open source CSS+Javascript based powerful XOXO outline editor

XML-based standards | Semantic HTML