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Re: Sometimes an empty value means "use the default value" and sometimes it doesn't ... right?

From: Costello, Roger L. <costello@mitre.org>
Date: Thu, 23 Aug 2012 19:32:52 +0000
To: "xmlschema-dev@w3.org" <xmlschema-dev@w3.org>
Message-ID: <B5FEE00B53CF054AA8439027E8FE17751E62FB13@IMCMBX04.MITRE.ORG>
Ken, Hello,

Sorry, I was not clear in my message.

I was not asking a question about semantics or meaning.

I was asking a question about the behavior of XML Schema validators.

Hopefully this question will be clearer:

    The XML Schema validator determines the
    value of the empty Altitude element
     to be the default, 100.

    The XML Schema validator determines the
    value of the empty Title element
     to not be the default; instead the value
    is the empty string.



At 2012-08-23 19:04 +0000, Costello, Roger L. wrote:
>Thus sometimes an empty value means "use the default value" and 
>sometimes it doesn't.  Right?

What something "means" is up to the semantics of the applications 
that act on the content, and to the vocabulary designers who are 
trying to impose common understandings of use amongst those employing 
the vocabulary.

To add to your list, in UBL an empty value means "error" ... there is 
an instance rule that no element shall be empty because it could be 
ambiguous between trading partners.

   "Use of empty elements within XML instance documents is a
    source of controversy for a variety of reasons."

I hope this helps.

. . . . . . . . . Ken

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Received on Thursday, 23 August 2012 19:33:24 UTC

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