[NeXus-definitions-tickets] [NeXusDefinitions] #266: implement difference in rules between base classes and application definitions

[NeXus Base Classes and Instrument Definitions]

#266: implement difference in rules between base classes and application
definitions
-------------------------+--------------------------
 Reporter:  Pete Jemian  |       Owner:  Pete Jemian
     Type:  defect       |      Status:  new
 Priority:  major        |   Milestone:
Component:  general      |  Resolution:
 Keywords:  NXDL schema  |
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Comment (by Pete Jemian):

 The **root element** of NXDL files is defined in the XML Schema file
 ({{{nxdl.xsd}}}) using the {{{<xs:element name="definition" ...}}}
 element.  How can we replace this with an either/or rule for the root
 element?  Since the {{{xs:choice}}} element is not allowed at this point,
 it seems impossible.  Using a {{{substitutionGroup}}} attribute to the
 {{{xs:element}}} element, we can simply rename {{{definition}}} to be
 either {{{base_class}}} or {{{application}}} but that does not change the
 associated {{{type}}} attribute.  This points to one {{{.xsd}}} file for
 base classes and a separate {{{.xsd}}} file for application definitions.
 That's what we have now, sort of, sharing the definitions of their common
 set of rules.

 ...

 Needs more thought.  For now, we leave in place with the {{{xs:redefine}}}
 elements in the subdirectories.

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Ticket URL: <http://trac.nexusformat.org/definitions/ticket/266#comment:12>
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NeXus Base Classes and Instrument Definitions