Detailed Tag Reference for package.xml version 2.0

Table of Contents
<channel> -- What is a channel?
<uri> -- When should I use <uri>?
<lead>, <developer>, <contributor>, and <helper> -- Developer documentation for a release
<version> -- versioning in package.xml 2.0
<stability> -- specifying release and API stability
<license> -- specifying software license and optional reference to license text
<contents> -- specifying the contents of a release
<dir> -- documenting a directory in the <contents> tag
<file> -- documenting a file in the <contents> tag
tasks for <file>s -- specialized file installation and manipulation
<compatible> -- Alleviating strict versioning with <compatible>
<dependencies> -- Dependency Specification in package.xml 2.0
<usesrole> -- documenting custom file roles used in <contents>
<usestask> -- documenting custom tasks used in <contents>
<phprelease>, <extbinrelease>, <extsrcrelease>, <bundle> -- specifying the content type of a release

Each tag that needs further explanation is documented here (unfinished)