Fragmentation Types
  - Different types of divergence have different impact
- Changed meanings can affect implementation support in authoring
& evaluation tools
    - dropped provisions
- reworded provisions 
- combined provisions
- split provisions
- added provisions
- Interim hybrid versions 
- Supersets (WCAG 1.0 plus internationalization, device
independence, usability, etc) 
    - not a fragmentation concern, but may go unsupported