Proposal: Inclusion of user defined gradients using graphics/SVG in the Office specification

Title: Message

I propose keeping the existing gradient specification in it's current form. 
In order to allow others to extend this specification, we should add an 
attribute to allow users to create their own 'gradient' types. By allowing a 
vector format such as SVG to describe this gradient type, we can handle cases 
that we cannot previously predict. The changes to the format are:

  
Add userdefinedgradient to the list of 
  gradient-style that can be supported. 
  
    
      
<!ENTITY % gradient-style 
      "(linear|axial|radial|ellipsoid|square|rectangular|userdefinedgradient)">

  
Add draw:userdefinedgradient to the attribute list of 
  draw:transparency and draw:gradient. 

  
    
This would be an XLINK to 
    access the graphic stored within 
    the overall file that would 
    define the gradient. The size would be defined by the view within the 
    graphic. The top-left, bottom right 
    coordinate of the view of the graphic would be scaled to the size of 
    the item being affected by the gradient.

  
Add 
  draw:userdefinedgradientitem to the an appropriate 
  section to hold the gradient rendering information. The XLINK/URL would 
  reference/index this item. 

  
    
Would contain the graphic and 
    gradient co-ordinate/transformation information.
    
The mapping system will be defined inside 
    of the gradient descriptor, such as to use 
    Red component, RGB component, brightness component, or ALPHA component from 
    the graphic itself. This will be an attribute corresponding to the info to 
    use from the graphic.
    
RGB, R, G, 
    B, ALPHA, H, S, B, C, M,Y, K are all color systems that should be able to be 
    used from the original graph.