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Length of a QName (ie length of a tuple)

From: Eric van der Vlist <vdv@dyomedea.com>
Date: Thu, 18 Oct 2001 16:37:53 +0200
Message-ID: <3BCEE941.6050506@dyomedea.com>
To: xmlschema-dev@w3.org
Knowing that:

http://www.w3.org/TR/xmlschema-2/#QName

[Definition:]   QName represents XML qualified names. The ·value space· 
of QName is the set of tuples {namespace name, local part}, where 
namespace name is an anyURI and local part is an NCName. The ·lexical 
space· of QName is the set of strings that ·match· the QName production 
of [Namespaces in XML].

.../...

QName has the following ·constraining facets·:

     * length
     * minLength
     * maxLength

And that:

http://www.w3.org/TR/xmlschema-2/#rf-length

For string and datatypes ·derived· from string, length is measured in 
units of characters as defined in [XML 1.0 (Second Edition)]. For 
anyURI, length is measured in units of characters (as for string). For 
hexBinary and base64Binary and datatypes ·derived· from them, length is 
measured in octets (8 bits) of binary data. For datatypes ·derived· by 
·list·, length is measured in number of list items.

.../...

·length· provides for:

     * Constraining a ·value space· to values with a specific number of 
units of length, where units of length varies depending on {base type 
definition}.

It seems that:

1) The length of a QName is currently undefined (QName is a primitive 
datatype and thus not derived from string, anyURI, hexBinary or 
base64Binary.

2) The length of a QName should measure the value space, ie the "tuple 
{namespace name, local part}".

Should it be length(namespace name) + length (local part) which are both 
defined?

Eric

BTW: is there any reason to define constraints on the lenght of a QName?

PS: the length of a xs:NOTATION is undefined for the same reason...
-- 
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Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
http://xsltunit.org      http://4xt.org           http://examplotron.org
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Received on Thursday, 18 October 2001 10:37:39 GMT

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