[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

Re: derivation by restriction and the use attribute

• To: "Helmut Dirtinger" <helmut_dirtinger@h...>
• Subject: Re: derivation by restriction and the use attribute
• From: ht@i... (Henry S. Thompson)
• Date: Mon, 13 Sep 2004 09:55:53 +0100
• Cc: <xml-dev@l...>
• In-reply-to: <BAY14-DAV18oRdUYPuj000c5fa3@h...> (Helmut Dirtinger'smessage of "Sat, 11 Sep 2004 12:49:37 +0200")
• References: <BAY14-DAV18oRdUYPuj000c5fa3@h...>
• User-agent: Gnus/5.1006 (Gnus v5.10.6) XEmacs/21.4 (Security ThroughObscurity, linux)

"Helmut Dirtinger" <helmut_dirtinger@h...> writes:

> I am currently experimenting with derivation by restriction and
> attribute declarations. I tried all combinations of changing the
> attribute use="required|prohibited|optional" from the base type to
> the derivation.

The Schema REC [1] says the following on this question:

  2 For each attribute use (call this R) in the {attribute uses} the
    appropriate case among the following must be true:

    2.1 If there is an attribute use in the {attribute uses} of the
       {base type definition} (call this B) whose {attribute
       declaration} has the same {name} and {target namespace}, then all
       of the following must be true:
       2.1.1 one of the following must be true:
             2.1.1.1 B's {required} is false.
             2.1.1.2 R's {required} is true.

. . .

  3 For each attribute use in the {attribute uses} of the {base type
    definition} whose {required} is true, there must be an attribute
    use with an {attribute declaration} with the same {name} and
    {target namespace} as its {attribute declaration} in the
    {attribute uses} of the complex type definition itself whose
    {required} is true.

These constraints apply at the component level, so 'prohibited'
translates into no attribute at all.  Accordingly I read the allowed
cases as

       B        R

     required  required
     optional  required          [your case 2]
     optional  optional
     optional  [prohibited]      [your case 1]

> SQC grants three combinations: case 1 and 2 and a third one:
>
> (3) Basetype: use="required" Subtype:use="prohibited"

To my surprise, I find that SQC2.2 does indeed allow this case.  This
seems to me to be a mistake, as it violates clause (3) above.

> So my question concerns the validity of this third case. Is this
> case valid?

I don't think so.

ht

[1] http://www.w3.org/TR/2004/PER-xmlschema-1-20040318/#coss-ct
-- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
    2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
            Fax: (44) 131 650-4587, e-mail: ht@i...
                   URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]

• References:
  • derivation by restriction and the use attribute
    • From: "Helmut Dirtinger" <helmut_dirtinger@h...>

• Prev by Date: automatically generate ID attribute for XML element
• Next by Date: RE: automatically generate ID attribute for XML element
• Previous by thread: derivation by restriction and the use attribute
• Next by thread: Pedant fuel: charset detection
• Index(es):
  • Date
  • Thread