User interface of the PROGRES interpreter:

   Sometimes, the PROGRES interpreter marks unexpected parts of a specification
   as the current interpreter increment. Furthermore, switching back from
   "dark grey" for backtracking mode to "light grey" for normal execution
   mode occurs sometimes too late or in unexpected cases (especially witin use-
   expressions). This does not affect the correctness of the produced results.

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Undo/Redo of interpreter actions:

   User undo/redo of interpreter actions is limited in the following way:
   undo of backtracking actions and cross session boundaries is still not
   possible.

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Switching between editing and execution activities:

   Editing a specification which is currently executed and continuing 
   execution afterwards is possible as long as changes are restricted to
   the body of transaction/productions/... without incarnations on the
   runtime stack. In all remaining cases execution should be terminated
   "gracefully" (with the option of undoing editing activities and
   continuing execution afterwards).

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Attribute access of graph browsers: 

   Currently, our graph browsers are not able to trigger (re-)evaluation
   of derived attributes with undefined values. Therefore, all those (derived)
   attributes which are not accessed by the PROGRES interpreter beforehand
   are displayed with undefined value.

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Cut&Paste of increments with manually modified layout:

   Cut&Paste should preserve any manual modifications of the layout
   of textual as well graphical parts of a specification. But in
   some cases these additional layout information gets lost (especially
   when keywords are rearranged which do not represent a complete logical
   increment of the specification, as for instance brackets).

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Cardinality constraints for attributes and edges:

   Analysis of specifications is not able to find all possible violations
   of cardinality constraints. Checking these constraints at runtime is delayed
   to the first read access.

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Recovery mechanisms for the PROGRES specification database:

   There are still cases, where PROGRES system crashes corrupt the specification
   database. Therefore, please make use of text backups and save any important
   intermediate state of your specification as a text backup file.

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Constraint-Evaluation must be handled carefully:

   Be aware of the fact that constraints are the latest addition of the 
   language PROGRES. It is, therefore, probable that their realization
   contains a number of bugs. Furthermore their usage is not tested in
   the prototyping framework and therefore not available yet.

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