The file structure of a pigment

A pigment is one single file. It is a gzipped tar archive (.tar.gz) of other files, but it has the extension .pigment .
Its mime-type is application/x-pigment
The archive should contain:

• A folder named data, which contains the uncompressed files necessary to activate the pigment. For example, a icon set pigment would contain the folder of the icons under data.
• A folder named information, containing:
  • One XML file with text only information concerning the pigment
  • A preview image

(Should we allow a file to include several pigments? This would make it easier for people with no Internet access to distribute skins) (Implemented in packs)