VHDL Issue Number:      1118
Classification:         Language Deficiencies and Modeling Problems
Language Version:       VHDL-93
Summary:                Group constituent can't be user-defined attribute name.
Related Issues:         
Relevant LRM Sections:  4.7, 
Key Words and Phrases:  group, group declaration, group constituent, attribute
                        name, user-edfined attribute
Current Status:         Submitted
1076-1993 Disposition:  N/A
Disposition Rationale:  N/A
Superseded By:          N/A
-----------------------
Date Submitted:         1995/07/26
Author of Submission:   Daniel S. Barclay
Author's Affiliation:   COMPASS Design Automation, Inc.
Author's Post Address:  5457 Twin Knolls Rd.
                        Suite 100
                        Columbia, MD  21045  USA
Author's Phone Number:  410-992-5700
Author's Fax Number:    410-992-3536
Author's Net Address:   daniel@compass-da.com
-----------------------
Date Analyzed:          TBD
Author of Analysis:     TBD
Revision Number:        $Revision: 1.1 $
Date Last Revised:      $Date: 1995/07/26 20:49:41 $


Description of Problem
----------------------
Section 4.7 disallows the use of attribute names as group constituents.  The
third text paragraph says:

	A name that is a group constituent may not be an attribute name (see 
	6.6), nor, if it contains a prefix, may that prefix be a function call.

The intent of the prohibition against attribute names is to prevent references
to predefined attributes.  This makes sense, considering that the purpose of 
groups is to associate an (ordered) set of named entities together, and that
predeine attributes are not normal, plain named entities..

However, disallowing all attribute names also prevents references to user-
defined attributes.  This is unnecessary because user-defined attributes are 
constants, and constants are named entities, and therefore user-defined 
attribute are named entities just as other named group constituents.  It is
irregular because normally user-defined attribute are not differentiated from
other constants.

This problem appears to result from using only syntactic concepts (the form
of the name) instead of semantic ones (what the name denotes) to implement 
the needed restriction.


Proposed Resolution
-------------------
Narrow the restriction to disallow only those attribute names that denote 
predefined attributes.


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


VASG-ISAC Recommendation for IEEE Std 1076-1993
-----------------------------------------------
TBD


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