Why specify the XML Schema Definition file?

XML schema definition (xsd) file are used by XML editors to provide validation and syntax hints when editing the configuration files. They are also used by the dispatcher to validate the application configuration.

When you create a configuration file for the Genero Application Server or for an application, you provide the path to an XML schema definition file (xsd)

In the GAS configuration file (as.xcf by default), this entry exists:
```
xsi:noNamespaceSchemaLocation="http://www.4js.com/ns/gas/3.20/cfas.xsd"
```
For external Web application configuration files, this entry should exist:
```
xsi:noNamespaceSchemaLocation="http://www.4js.com/ns/gas/3.20/cfextwa.xsd"
```
For Web services application configuration files, this entry should exist:
```
xsi:noNamespaceSchemaLocation="http://www.4js.com/ns/gas/3.20/cfextws.xsd"
```

The XML editor either looks on the Web or in its local schemas catalog for the specified XML schema definition file.

While the Genero Application Server validates the configuration files, it does not rely on these entries within the configuration files themselves. The validation is completed by the dispatcher using the schemas provided in $FGLASDIR/etc.