VHDL Issue Number:      0244
Classification:         Language Definition Problem
Language Version:       VHDL-87
Summary:                The meaning of a qualified expression is in dispute
Related Issues:         
Relevant LRM Sections:  7.3.4
Key Words and Phrases:  Qualified expressions, matching elements
Current Status:         Submitted
1076-1993 Disposition:  Superseded (ISAC Issues Outstanding)
Disposition Rationale:  N/A
Superseded By:          1073
-----------------------
Date Submitted:         1991/09/19
Author of Submission:   Doug Dunlop
Author's Affiliation:   Intermetrics, Inc.
Author's Post Address:  4733 Bethesda Ave, #415
                        Bethesda, MD  20814
Author's Phone Number:  (301) 657-3775
Author's Fax Number:    
Author's Net Address:   dunlop@inmet.inmet.com
-----------------------
Date Analyzed:          TBD
Author of Analysis:     TBD
Revision Number:        $Revision: 1.10 $
Date Last Revised:      $Date: 1995/05/13 21:53:48 $


Description of Problem
----------------------
A customer has explained to me that Valid and CLSI give different meanings
to certain qualified expressions.

In particular, consider the case of a qualified expression
      type_mark'(expression)
where type_mark is a constrained array subtype.  Furthermore, suppose the
direction of this subtype differs from that of the expression but
nevertheless there are "matching elements" between the 
subtype and the value of the expression.

In this case should the evaluation of the qualified expression result in
a run-time error because the value of the expression does not belong "to
the subtype denoted by the type mark"?


Proposed Resolution
-------------------
The direction mismatch in this case should cause the subtype check required
in 7.3.4 to fail.


VASG-ISAC Analysis & Rationale
------------------------------
TBD


VASG-ISAC Recommendation for IEEE Std 1076-1987
-----------------------------------------------
TBD


VASG-ISAC Recommendation for Future Revisions
---------------------------------------------
TBD