Yes, DITA attributes can have default values. Default values are predefined values that are automatically assigned to an attribute if no explicit value is provided for that attribute in the content. This feature provides a way to ensure that attributes always have a meaningful value, even if content creators don’t specify one.

In DITA, attribute default values are defined in the DITA specialization schema or the DITA document type definition (DTD). When a default value is defined for an attribute, it is associated with a specific element or attribute type.

When content is authored using DITA, content creators can choose to specify a value for an attribute explicitly. If they do, the provided value takes precedence over any default value defined in the schema or DTD.

If a content creator does not provide a value for an attribute, the default value defined in the schema or DTD is automatically assigned to that attribute. This ensures that the attribute always has a value, even if it is not explicitly specified in the content.

Default values are helpful in ensuring consistency, creating a fallback value, and automation.

Consistency:

Default values ensure that attributes have consistent values across content when authors do not provide explicit values. This helps maintain a uniform structure and behavior in DITA documents.

Fallback:

Default values can serve as fallback values when authors omit attribute values. This ensures that essential metadata or information is not missing from the content.

Automation:

Default values can be used to automate certain processes or behaviors based on predefined settings. For example, default values can trigger specific conditional processing actions when no explicit attribute value is provided.

Example:

A DITA specialization for creating product documentation uses a custom attribute called @product-version, defined for the <feature> element. The specialization schema specifies that if a @product-version value is not explicitly provided in a <feature> element, it should default to “1.0.”

<!– DITA Specialization Schema –>

        <specialization>
    <attlist>
        <attribute name="product-version">
            <default>"1.0"</default>
        </attribute>
    </attlist>
</specialization>
    

Now, when authors create content using this specialization, they can include the @product-version attribute with a specific value for a <feature> element:

        <feature product-version="2.0">
    <title>New Feature</title>
    <description>This is a description of the new feature.</description>
</feature>
    

In this example, the @product-version attribute is explicitly set to “2.0” for the <feature> element. However, if the author had not provided a value, the default value of “1.0” defined in the specialization schema would have been automatically assigned to the attribute. This ensures that all <feature> elements have a @product-version value, either explicitly specified or defaulted.