4. Namespaces & schemas¶

A namespace must be identified for each prefix using the @xmlns:prefix attribute.

Important

The client must use the same version of a namespace as the server! The current namespace versions are listed in the greeting (see Service discovery).

If the versions in the documentation differ from the versions in the greeting, follow the versions in the greeting.

To enable XML validation on the client side, depending on the selected XML-validation tool, there are 2 options:

to link a namespace to the location of a schema (see the table below) inside messages using the @xsi:schemaLocation attribute, for the tool to locate the schema from here – this option is illustrated in structure descriptions, or
to pass the location of the global schema as an argument to the XML-validation tool directly, such as:
```
xmllint --noout --schema "/usr/share/fred-client/schemas/all.xsd" -
```

The FRED EPP server as such does NOT require schema locations inside messages and ignores them if they are present.

The global schema all-2.4.0.xsd (alias all.xsd) imports the following partial schemas and thus provides the definitions of all namespaces in a single file.

Prefix 1	Namespace identifier	Schema file (partial)	Description
`epp` or default	`urn:ietf:params:xml:ns:epp-1.0`	`epp-1.0.xsd`	Extensible Provisioning Protocol v1.0 Protocol base (generic message structure)
`eppcom`	`urn:ietf:params:xml:ns:eppcom-1.0`	`eppcom-1.0.xsd`	Extensible Provisioning Protocol v1.0 Shared structures
`fred`	`http://www.nic.cz/xml/epp/fred-1.5`	`fred-1.5.0.xsd`	FRED EPP protocol extensions
`fredcom`	`http://www.nic.cz/xml/epp/fredcom-1.2`	`fredcom-1.2.1.xsd`	FRED EPP protocol extensions Shared structures
`domain`	`http://www.nic.cz/xml/epp/domain-1.4`	`domain-1.4.2.xsd`	FRED object extension for domain provisioning Command-response mapping and structures
`contact`	`http://www.nic.cz/xml/epp/contact-1.6`	`contact-1.6.2.xsd`	FRED object extension for contact provisioning Command-response mapping and structures
`nsset`	`http://www.nic.cz/xml/epp/nsset-1.2`	`nsset-1.2.2.xsd`	FRED object extension for nsset provisioning Command-response mapping and structures
`keyset`	`http://www.nic.cz/xml/epp/keyset-1.3`	`keyset-1.3.2.xsd`	FRED object extension for keyset provisioning Command-response mapping and structures
`enumval`	`http://www.nic.cz/xml/epp/enumval-1.2`	`enumval-1.2.0.xsd`	FRED command/response extensions for ENUM domains
`extra-addr`	`http://www.nic.cz/xml/epp/extra-addr-1.0`	`extra-addr-1.0.0.xsd`	FRED command/response extensions for a mailing address in contacts
`xsi`	`http://www.w3.org/2001/XMLSchema-instance`	N/A	Namespace for an XML Schema instance Required when the `@xsi:schemaLocation` attribute is used.
`xs`	`http://www.w3.org/2001/XMLSchema`	N/A	Namespace for the XML Schema Used only in this manual.

1: These prefixes are used throughout this manual and some of them in schemas but you are not bound to use the same prefixes in your implementation. It is important just to assign correct namespace identifiers to prefixes.