MDDL: Content - Extending

Extending MDDL
It is possible the MDDL specification may not include terms or other content that is needed for a specific application. In such cases it is necessary to extend MDDL as described here.

DO NOT EXTEND MDDL UNLESS ABSOLUTELY NECESSARY. Instead, Contact Us so we may add whatever content to the specification that is of interest to you.

Extending MDDL requires specific support from the organization that extends the schema:

A valid W3C Schema (.xsd) representing the content must be created.

The Schema must be made available to all possible recipients of the MDDL Instance Document. Theoretically, it could be placed at the URI (URL) that defines the namespace of the schema.

The organization must be prepared to provide support for the deviation to all recipients of the schema.

Depending on the scope of the extension, support could be a non-trivial issue.

The MDDL W3C Schema does not allow extensions within an MDDL Instance Document EXCEPT within the "other" element. The "other" element is included as a child to nearly all MDDL elements so anything can be extended. Extensions should be made consistent with XML guidelines as well as the philosophy of MDDL.

An extension of an MDDL Property (anything with a Base Type other than "Container") should be a property that qualifies, clarifies, or otherwise provides enhancement to the property being extended.

An extension of an MDDL Container specifies an additional property that is relevant to the content of that container.

In the event it is not clear within which "other" element an extension should occur, PLEASE SEEK GUIDANCE. Most non-conformant content should be placed within the domain it extends, or in some cases with the main "snap" element.

Within an "other" extension, an organization's proprietary content can be co-mingled with MDDL elements. Thus, whenever possible, an extension should use MDDL terms where appropriate instead of defining specific private forms of existing MDDL terms.

Click here to download an example utilizing an extension (by a fictitious organization). Click here to see the schema that must be maintained.