Why you should avoid Notation Declarations

R

Razvan

Hi,




In an article by Mr. Kohsuke Kawaguchi found at:

http://www.xml.com/pub/a/2001/06/06/schemasimple.html?page=2

he explains why notations should be avoided. The following XML Schema
is provided:


<xsd:notation name="jpeg" public="image/jpeg" system="viewer.exe" />

<xsd:element name="picture2">
<xsd:complexType>
<xsd:simpleContent>
<xsd:extension base="xsd:hexBinary">
<xsd:attribute name="pictype">
<xsd:simpleType>
<xsd:restriction base="xsd:NOTATION">
<xsd:enumeration value="jpeg"/>
<xsd:enumeration value="png"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:attribute>
</xsd:extension>
</xsd:simpleContent>
</xsd:complexType>
</xsd:element>


The following XML is OK:

<picture pictype="jpeg"> ... </picture>

and so is this: (I tested with XML Spy 2005 and XSV 2.8-1)

<pic:picture pictype="jpeg"> ... </pic:picture>

but the author says that the later form is invalid:

"
But the following fragment is not valid even if the prefix "pic" is
properly
declared.
<pic:picture pictype="jpeg"> ... </pic:picture>
Confused? You have to write it as follows because it's a QName.
<pic:picture pictype="pic:jpeg"> ... </pic:picture>
Apparently it fails to serve its only reason for existing. There's
really no
reason to use notations. Notations are for SGML.
"

Can somebody explain why notations are bad and they should be avoided
?



Regards,
Razvan
 

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