VHDL Issue Number:      0055
Classification:         Language Definition Problem
Language Version:       VHDL-87
Summary:                Why must a name in a wait stmt. sens. list be static?
Related Issues:         None.
Relevant LRM Sections:  8.1
Key Words and Phrases:  Sensitivity list, wait statement, static signal name
Current Status:         Submitted
1076-1993 Disposition:  Superseded (ISAC Issues Outstanding)
Disposition Rationale:  N/A
Superseded By:          1017
-----------------------
Date Submitted:         1991/01/15
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
----------------------
LRM 8.1 requires that each name appearing in the sensitivity list of a
wait statement be a static name.  The subject of this IR is the underlying
rationale behind this language rule.

The rule became suspicious when it was pointed out that one could have
a signal parameter in the sensitivity list of a wait statement.  Although
the name of a signal parameter is technically "static", it does not match
the intuition behind a static signal name in that one cannot determine
(statically) from the name the true signal being waited on.

Roughly speaking then, it seems like if an implementation can allow a
signal parameter in the sensitivity list of a wait statement, the
implementation should be able to cope with *any* signal name in the
sensitivity list of a wait statement.  Was the rule requiring static
signal names in wait statement sensitivity lists motivated by something
other than ease of implementation?


Proposed Resolution
-------------------
Language experts should explain how it can be that a signal parameter can
appear in the sensitivity list but a non-static signal name cannot.  If good
justification cannot be given for this apparent discrepancy, perhaps the
language should be revised.


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


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


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