Epidermis' customisation unit: pigment

In order to keep Epidermis' customisations both customisable and complete, a structure involving pigments and skins was created.
A pigment is a customisation of a piece of the GNOME desktop. It contains the files necessary to activate the customisation, (with the exception of skins,) and the information describing it, including authorship, copyright, name, key words, description, main colours and a preview image.
A pigment type is a category of pigments sharing the same characteristics of the area of the GNOME desktop they affect using the same technology, for example, pigment types can include: Metacity, wallpaper, GDM login screen... Metacity and Emerald are seperate pigment types, because they use different technology.
A skin is a pigment of the type skin, it is unique in the fact that it includes links to other pigments required for the activation of the skin. It should link to (at least?) one pigment of every type (other than skin). The skin is the means through which both complete and rapid customisation occurs.