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Antwort: Re: Global Vs Root Element.

From: <Holger.Joukl@LBBW.de>
Date: Fri, 6 Jul 2001 11:55:06 +0200
Message-Id: <200107060939.LAA28121@bank.de>
To: ijs@decisionsoft.com
Cc: xmlschema-dev@w3.org

one (beginner´s :-) question:
Are you allowed to put in the <attribute name=...> in element content?

-- snip------------------------------------------------------------
<group name="fooStyleX">
  <element name="foo">
    <attribute name="some_attr">

or similar with the <group...> as element content:

<element name="doc">
  <element name="a">
    <group ref="fooStyleX" />

Or are you just leaving out some anonymous complexType "wrappers"
around this content? (Maybe that´s what you mean with "pseudo XSDL")

As I understand the Rec, element content is restricted to:

"(annotation?, ((simpleType | complexType)?, (unique | key | keyref)*))"



Holger Joukl
2342 Z - IT/Org II Handel
Tel. +49 (711) 124 - 7078

                    Ian Stokes-Rees                                                                                                          
                    <ijs@decisionsoft.        An:     Venkateswar Wunnava <wvsvenkat@worldnet.att.net>, wason@mindspring.com, Jeff Rafter    
                    com>                      <jeffrafter@definedweb.com>, xmlschema-dev@w3.org                                              
                    Gesendet von:             Kopie:                                                                                         
                    xmlschema-dev-requ        Thema:  Re: Global Vs Root Element.                                                            
                    06.07.01 11:02                                                                                                           

I have just realised that another side effect of using groups to wrap
elements allows one to have multiple elements with the same name made
available for referencing.  Imagine:

  <foo some_attr="..."/>
  <foo another_attr="..."/>
  <foo some_attr="..."/>

You may want the first and third "foo" to be the same and be placed inside
and "c" as references, however also place the second "foo" inside "b" by
reference.  This could be achieved by creating (as always, in pseudo XSDL):

<group name="fooStyleX">
  <element name="foo">
    <attribute name="some_attr">

<group name="fooStyleY">
  <element name="foo">
    <attribute name="another_attr">

<element name="doc">
  <element name="a">
    <group ref="fooStyleX" />

  <element name="b">
    <group ref="fooStyleY" />

  <element name="c">
    <group ref="fooStyleX" />

Ian Stokes-Rees wrote:
> [I missed the first part of this thread, so appologies for any repeated
> information]
> [actually terminology discussion is in the second part of this email]
> Global Elements
> ---------------
> Global elements refer to elements defined as the immediate children of
> <schema> element in an XSDL document (a schema definition document).
> have three purposes:
> 1) to define elements which can be used be reference (i.e. <element
> ref="some_global_element" />) _within_ other element, group, or type
> definitons; and,
> 2) to define elements which can be legal document elements in instance
> documents; and,
> 3) to define elements which can be used in instance documents where the
> document's schema specifies <any> element may exist.
> If you wish to define an element to be used only for <element ref="..."/>
> purposes, the exact same semantics can be achieved by dropping this
element in
> a <group> element (I cannot take credit for this -- it was suggested to
me on
> this list some months ago).  The following pseudo XML/XSDL gives the
> idea:
> Instance:
>   <globalEle>
>     <refEle>
>   </globalEle>
> Schema Before:
>   <element name="refEle" type="myType" />
>   <element name="globalEle" >
>     <element ref="refEle" />
>   </element>
> After:
>   <group name="refEle">
>     <element name="refEle" type="myType" />
>   </group>
>   <element name="globalEle" >
>     <group ref="refEle" />
>   </element>
> With the first schema, the following document would be schema valid:
> <refEle />
> But this would not be legal with the second schema.  The only issue then
> decide on is the naming convention for the group.  There is no name
> since groups are in a different space from global element names, so this
> the "appearance" of an element ref to "refEle".  I am still undecided
> how "nice" it is to do this (have groups and elements with the same
name).  It
> may not be unreasonable if restricted to _only_ these circumstances.

Ian Stokes-Rees                       DecisionSoft Ltd.
Telephone: +44-1865-203192            http://www.decisionsoft.com


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Received on Friday, 6 July 2001 05:57:38 UTC

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