The metadata attributes express qualifications on the content. These qualifications can be used to modify the processing of the content.
One typical use of the metadata attributes is to filter content based on their values. Another typical use is to flag content based on their values, for example by highlighting the affected text on output. Typically audience, platform, product, and otherprops are used for filtering, and the same attributes plus rev are used for flagging. Status and importance are used for tool-specific or transform-specific behavior, for example marking steps in a task as optional or required.
In general, a metadata attribute provides a list of one or more qualification values, separating those values with whitespace. For instance, an audience attribute of administrator programmer qualifies the content as applying to administrators and programmers.
For a topic, the audience, platform, and product metadata can be expressed with attributes on the topic element or with elements within the topic prolog. While the metadata elements are more expressive, the meaning of the values is the same, and can be used in coordination: for example, the prolog elements can fully define the audiences for a topic, and then metadata attributes can be used within the content to identify parts that apply to only some of those audiences.
The values in the audience attribute may also be used to reference a more complete description of an audience in an audience element. Use the name of the audience in the audience element when referring to the same audience in an audience attribute.
The audience attribute takes a blank-delimited list of values, which may or may not match the name value of any audience elements.
The platform attribute takes a blank-delimited list of values, which may or may not match the content of a platform element in the prolog.
The product attribute takes a blank-delimited list of values, which may or may not match the value of the prodname element in the prolog.
The product attribute takes a blank-delimited list of values, which may or may not match the values of othermeta elements in the prolog.
The attribute can also take labelled groups of values. A labelled group consists of a string value followed by an open parenthesis followed by one or more blank-delimited values followed by a close parenthesis. The simple format is sufficient when an information set requires only one additional metadata axis, in addition to the base metadata attributes of product, platform, and audience. The full format is useful when an information set requires two or more additional metadata axes. A process can detect which format is in use by the presence of parentheses in the attribute.
For example, a simple otherprops value list: <codeblock otherprops="java cpp">
For example, a complex otherprops value list: <codeblock otherprops="proglang(java cpp) commentformat(javadoc html)">
OASIS DITA Architectural Specification v1.0 -- 09 May 2005
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