Bottom Level Data definitions
Composite data definitions
Relations among composite data
Ways of specifying new composites and relations  (templates)
First User Interface (ala etude)
Behaviors of markers
  in display
  in node creation
  to applications
Markers have been replaced by regions.
Operations do their work by traversing subtrees delineated by regions.
The operations array gives the specific C procedures that perform
operations common to all(?) nodes.

Scheduling and Propagation
  What to do
  When to stop
  Over what region
    markers
    pointers
    multiple dependencies
      spelling
Dependency -- Operation matrix
  Thing cared about
  Thing that cares
  Routine to run -- specific to subthing actually changed)

Distributed dependency matrix
Central Event Queue

Enroll/Un-enroll
  Delete of pending (one type)
  Wait for pending (other type)
  Enroll/Un-enroll is an event to be queued.

Redisplay
  Bitblt of rectangular regions which have changed
  Keep in mind the scope of a rectangle to check for changes
  Dont want to test 1k X 1k every character input, do we!