Re: redefinition of SimpleType in nested schemas

Hi Marie,

Substitution groups have also constraints. The type of the specialized 
subject element needs to be validly derived from the Subject type

http://www.w3.org/TR/xmlschema-1/#e-props-correct
***
4 If there is a {substitution group affiliation}, the {type definition} 
of the element declaration must be validly derived from the {type 
definition} of the {substitution group affiliation}, given the value of 
the {substitution group exclusions} of the {substitution group 
affiliation}, as defined in Type Derivation OK (Complex) (§3.4.6) (if 
the {type definition} is complex) or as defined in Type Derivation OK 
(Simple) (§3.14.6) (if the {type definition} is simple).
***

Assuming a definition for Subject type and element as

     <xs:simpleType name="Subject">
         <xs:restriction base="xs:string">
             <xs:enumeration value="a"/>
             <xs:enumeration value="b"/>
         </xs:restriction>
     </xs:simpleType>

     <xs:element name="Subject" type="Subject"/>

then following to Type Derivation OK (Simple) (§3.14.6)
http://www.w3.org/TR/xmlschema-1/#cos-st-derived-ok

***
Schema Component Constraint: Type Derivation OK (Simple)
For a simple type definition (call it D, for derived) to be validly 
derived from a type definition (call this B, for base) given a subset of 
{extension, restriction, list, union} (of which only restriction is 
actually relevant) one of the following must be true:
1 They are the same type definition.
2 All of the following must be true:
2.1 restriction is not in the subset, or in the {final} of its own {base 
type definition};
2.2 One of the following must be true:
2.2.1 D's ·base type definition· is B.
2.2.2 D's ·base type definition· is not the ·ur-type definition· and is 
validly derived from B given the subset, as defined by this constraint.
2.2.3 D's {variety} is list or union and B is the ·simple ur-type 
definition·.
2.2.4 B's {variety} is union and D is validly derived from a type 
definition in B's {member type definitions} given the subset, as defined 
by this constraint.
***

you can see that a new subject defined as

<xs:element name="NewSubject" substitutionGroup="Subject" 
type="NewSubject"/>

     <xs:simpleType name="NewSubject">
         <xs:union memberTypes="Subject">
             <xs:simpleType>
                 <xs:restriction base="xs:string">
                     <xs:enumeration value="c"/>
                     <xs:enumeration value="d"/>
                 </xs:restriction>
             </xs:simpleType>
         </xs:union>
     </xs:simpleType>

does not work. Only a restriction of the Subject type will work in this 
case.

Best Regards,
George
-- 
George Cristian Bina
<oXygen/> XML Editor, Schema Editor and XSLT Editor/Debugger
http://www.oxygenxml.com

On 9/22/10 3:29 PM, Marie Bilde Rasmussen wrote:
> Hi George,
> You are right. And Thankyou. I just found the same paragraph in the spec
> (grrrr!). I am ow considering a solution with a specialized vocabulary
> in a separate element, placed in substitution group with my <Subject>
> element as it's head. If substitution groups can't be <redefined>d, I'll
> allow these <specialized-subject>-elements in the most general schema -
> these elements probably won't bother my authors as much as if I expanded
> the Simpletype in it's original definition, forcing them to choose from
> a list of alternatives that would be far too long for them.
> Thanks again!
> best regards,
> Marie
> 2010/9/22 George Cristian Bina <[email protected]
> <mailto:[email protected]>>
>
>     Hi Marie,
>
>
>
>      > Danish-English-technical.xsd builds on it's turn upon
>      > Danish-English.xsd, but this time I have chosen to use <xs:redefine>,
>      > because in these special dictionaries, I need to modify the
>     SimpleType
>      > "Subject" by extension.
>     ------------^^^^^^^^^^^^^
>
>     The derivation methods for simple types are restriction, list and
>     union, extension is for complex types. In case of redefinitions of
>     simple types you can use only restriction, see
>     Schema Representation Constraint: Redefinition Constraints and Semantics
>     http://www.w3.org/TR/xmlschema-1/#src-redefine
>     ***
>     5 Within the [children], each <simpleType> must have a <restriction>
>     among its [children] and each <complexType> must have a restriction
>     or extension among its grand-[children] the ·actual value· of whose
>     base [attribute] must be the same as the ·actual value· of its own
>     name attribute plus target namespace;
>     ***
>
>     Best Regards,
>     George
>     --
>     George Cristian Bina
>     <oXygen/> XML Editor, Schema Editor and XSLT Editor/Debugger
>     http://www.oxygenxml.com <http://www.oxygenxml.com/>
>
>
>     On 9/22/10 2:23 PM, Marie Bilde Rasmussen wrote:
>
>         Hello.
>         I have an xml schema, let's call it dictionary.xsd, describing
>         general
>         structures and datatypes used in dictionaries. dictionary.xsd
>         contains a
>         definition of a SimpleType called Subjects. The SimpleType is a
>         restriction of xs:string and it contains a long list of
>         enumerations.
>         Another - more specialized - schema, called Danish-English.xsd
>         is built
>         upon dictionary.xsd. This is done by using <xs:include>.
>         A third - even more specialized - schema, called
>         Danish-English-technical.xsd builds on it's turn upon
>         Danish-English.xsd, but this time I have chosen to use
>         <xs:redefine>,
>         because in these special dictionaries, I need to modify the
>         SimpleType
>         "Subject" by extension.
>         I cannot figure out how to do this. I am not allowed to do so.
>         This has worked for me with only one level of inclusion. Could
>         the fact
>         that I want to redefine a schema on a level that is more than one
>         nesting leve l"away" be the problem?
>         below I have tried to illustrate the nesting and the Type
>         Definitions:
>         Danish-English-technical.xsd (redefines SimpleType "Subjects")
>         ->
>         redefines
>         Danish-English.xsd
>         ->
>         includes
>         dictionary.xsd (declares SimpleType "Subjects" as a restriction of
>         xs:string by enumeration)
>         I would be grateful for any input.
>         Regards,
>         Marie
>
>