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Re: Bug in XSV? ... reference without <import>

From: Roger L. Costello <costello@mitre.org>
Date: Mon, 07 May 2001 07:43:13 -0500
Message-ID: <3AF69861.E4F1F05@mitre.org>
To: costello@mitre.org, xmlschema-dev@w3.org
"Henry S. Thompson" wrote:
>
> They are right, XSV is wrong.  This is _not_ a "you can wait until
> runtime" issue.  

In an instance document, schemaLocation is optional.  As Noah always
reminds me, "schemaLocation is just a hint to a schema validator".  If
schemaLocation is optional in the instance document, then it seems
reasonable that an <import> element should be optional in a schema.  

It's too bad that it is not a "wait till runtime" issue.  That
capability would have provided a lot of power.  Without this capability
there is no way to create an element with a simpleType (e.g., sensors)
that can be extended by another schema - for example the boston_sensors
are barometer, thermometer, and anenometer.  For the London weather
station they need to extend the simpleType to include a hygrometer.  A
"dangling type" provided an ideal mechanism for implementing this
"replaceable simpleType".  I don't believe that that there is any way to
implement this capability.  /Roger
Received on Monday, 7 May 2001 07:42:27 GMT

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