Semantic version: major (required), minor (required), patch (optional, default=0).
Common HTTP image MIME types for banners, logos, etc.
Predefined roles for branding images.
Versioned branding descriptor. Contains a URI for the color palette
and zero-or-more image references (logos, banners, etc.) with metadata.
Reference to a previously-published image asset via URI,
with required ID (xs:ID), optional role, dimensions, and MIME type.