I'm wondering if a schema describing the format of the plugin.xml
files can be found somewhere? I've tried googling and searching the
eclipse news archives without much succes.
I've found references to something called "extension point schemas",
in eg.
http://www.eclipse.org/articles/Article-Plug-in-architecture/plugin_architecture.html
But I'm unsure what these "extension point schemas" are and what role
they play. It seems they are something other than what's normally
understood by XML schemas...?