[Bug 4602] NOTATION and enumeration

http://www.w3.org/Bugs/Public/show_bug.cgi?id=4602

           Summary: NOTATION and enumeration
           Product: XML Schema
           Version: 1.0/1.1 both
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: unclassified
          Severity: normal
          Priority: P2
         Component: Datatypes: XSD Part 2
        AssignedTo: cmsmcq@w3.org
        ReportedBy: sandygao@ca.ibm.com
         QAContact: www-xml-schema-comments@w3.org


(I remember raising this issue before, but couldn't find it in Bugzilla. Sorry
if it's a duplicate.)

In part 2 of both 1.0 and 1.1, NOTATION type has the following constraint:

"Schema Component Constraint: enumeration facet value required for NOTATION
It is an ·error· for NOTATION to be used directly in a schema.  Only datatypes
that are derived from NOTATION by specifying a value for ·enumeration· can be
used in a schema."

But it's not clear what "used directly in a schema" means.
- Used as a base type in a restriction
- Used as a member type in a union
- Used as an item type in a list
- Used as the declared type of an element/attribute
- Used as xsi:type in an instance
- Used to validate an element/attribute in an instance

My guess is that the last one is the ultimate goal. We may also have meant to
require all but the first 1 (as base type) to avoid the last one from
happening.

Some clarification seems to be in order.