Extensible metadata attributes

As an aid to information architects, extensible metadata attributes are part of the proposed DITA 1.1 standard, and are supported by DITA Open Toolkit 1.3.

Note: Because OASIS DITA 1.1 was not yet approved at the time DITA Open Toolkit 1.3 was released, the functionality described here should be considered preliminary until DITA 1.1 is approved, the 1.3 Toolkit assessed relative to DITA 1.1, and appropriate changes made to the Toolkit, if necessary.

Example

As a DITA information architect, you could:
1. Define new attributes that the team needs, for example "proglanguage".
2. Express each new attribute as a separate domain package, for example proglanguage.mod, with the new attribute specialized from the "props" attribute.
3. Integrate the domain packages into the authoring DTDs or schemas:
  1. Redefine the "props" attribute entity to include the "proglanguage" attribute. Similarly, you can redefine element entities to integrate new domain elements.
  2. Add the new attribute domain to the list of domains in the domains attribute, preceded by an "a", for example, domains="a(props proglanguage)".
As a writer, you could:
1. Add values to the new attributes of an element.
2. Define values in the DITA filter file.
3. Transform the DITA source files to remove or flag the content based on the new attributes, for example flagging all proglanguage="Java"
After you do that, another writer could reuse the content.
A specialization-unaware trademarking tool requires generalization of the contributed content. If the user runs all the content through the tool, the content is processed and filtered against the new attributes after the generalization. The new attributes are now collapsed into the "props" attribute.
1. The generalization turns proglanguage="Java" into props="proglanguage(Java)".
2. The conditional processing transform recognizes the new form as equivalent to the old, and the instruction "flag all proglanguage=java" operates on either props="proglanguage(Java)" or proglanguage="Java".