Why you should avoid Notation Declarations (by Kohsuke Kawaguchi)

[Razvan MIHAIU <mihaiu@mihaiu.name>]

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