XSchema Spec - XSchema Element (Sections 2.0 and 2.1), Draft 6

[Simon St.Laurent]

After an hour with the namespace draft, this is where I'm at.  If I'm wildly 
dead wrong, as is often the case when I'm dealing with namespaces, please let 
me know. The FIXED declaration for the xmlns attribute and the removal of 
prefixes from subelements appear to be the main issues.  I could change the 
attribute to xmlns:XSC and return the prefixes if that seems preferable.  (I'm 
planning on overriding it again in the Doc element, and allowing others to 
override it in the More element, if that's helpful.

Let me know!  Being wrong can be fun too.

As always, a prettier HTML version of this will be posted shortly at 
http://purl.oclc.org/NET/xschema. 

Simon St.Laurent
Dynamic HTML: A Primer / XML: A Primer / Cookies

2.0 XSchema Syntax

This section describes the XSchema document syntax. The XSchema document is an 
XML document containing a single XSchema element in which information 
describing the schema is nested. The XSchema element must be preceded by an 
XML declaration and may be preceded by other declarations, comments, and 
processing instructions.

2.1 The XSchema Element

The XSchema element is the root element for all XSchema documents. The 
declaration for the XSchema element is:

<!ELEMENT XSchema (Doc?, More?, Namespace*, (ElementDecl | AttDef | Model | 
Choice | Sequence | Mixed | Ref | Notation | XSchema)*)>
<!ATTLIST XSchema
    xmlns CDATA #FIXED "http://www.purl.org/NET/XSchema/v1"
    Version CDATA #FIXED "1.0"
    MimeType CDATA "application/xml"
    FileExtension CDATA "xml"
    id ID #IMPLIED>

The XSchema element contains other elements describing the XSchema and 
building a schema. These elements are described in later sections of this 
specification. The XSchema element may also contain other XSchema elements 
nested inside of it. This nesting of XSchema elements improves reusability of 
XSchemas by allowing the combination of multiple XSchemas inside of a single 
XSchema framework. It also allows finer-grained control over documentation for 
subsections of an XSchema.

The XSchema element's attributes include information about the namespace used 
by XSchema, the version of the XSchema specification used, and information 
about the type of documents described by the XSchema. 

The XSchema namespace is fixed with the xmlns attribute to correspond with the 
8/2/98 working draft of Namespaces in XML.

Information about the XSchema specification version used to create this 
XSchema, contained in the Version attribute, is critical to proper handling of 
documents should the specification be updated in the future. This 
specification is identified as version 1.0. Future major and minor versions of 
the XSchema specification should identify themselves differently. No provision 
is made at this time for nesting XSchemas using different versions of the 
specification under a parent XSchema element.

The MimeType and FileExtension attributes are used to provide a suggested MIME 
(Multipurpose Internet Mail Extensions) Content-type and file extension for 
documents created using a particular XSchema. Applications may use this 
information to identify XML document types. A document library that generates 
XML documents dynamically could assign file extensions and MIME types based on 
the XSchema used. 

Applications using this information should use the values stored in the first 
XSchema encountered during processing. For instance, if an XSchema includes 
another nested XSchema, the values for the MimeType and FileExtension 
attributes of the root XSchema should be used.

By default, most XML documents are assumed to have a MIME type of 
application/xml, as described in "XML Media Types" by E.J. Whitehead and 
Murata Makoto. Developers who need different MIME types for documents created 
using particular XSchemas may register other MIME types with the IETF, as 
described in RFC 1590, or use the 'x-' prefix syntax for subtypes, as 
described in RFC 1521.


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