About Arbortext Styler > Styling DITA Documents > Working with Specialized Elements
Working with Specialized Elements
Arbortext Styler provides fallback generalization support for specialized DITA elements. Arbortext Styler supports the DITA standard class attribute that enables an element to be labeled as a specialization of another element. When a specialized element is left Unstyled, Arbortext Styler and the publishing process treat occurrences of the specialized element as if they were the base element used for the specialization. This process is called generalization or fallback processing.
Note that for fallback generalization to work, you must have no references to the unstyled, specialized element in your stylesheet besides the definition that makes the element unstyled. For example, if you want fallback generalization to treat the concept element as an unstyled specialization of the topic element, you must not perform any of the following operation in Arbortext Styler:
Create a context for title in concept or any similar context.
Use concept as the scoping element for a table of contents.
Use concept as the element for which an attribute is tested in a condition.
Use concept in any XPath expressions.
This is only a partial list. In general, you should never use an unstyled, specialized element in any Arbortext Styler control where you can specify an element name. Arbortext Styler detects and reports most occurrences of these invalid references when you execute Tools > Validate Stylesheet, File > Export operations, or a preview operation. However, Arbortext Styler does not detect invalid references in XPath expressions.
Arbortext Styler supports fallback generalization in the following areas:
Arbortext Editor display - When you use an Arbortext Styler stylesheet to control display in Arbortext Editor, Arbortext Editor uses the styling developed for a base element when a specialized element is unstyled.
The specialized element and base element must both be in the stylesheet for fallback generalization to work in this case. Also, when you select a specialized element in Arbortext Editor that is unstyled, Arbortext Styler does not highlight that element in the Elements list. Instead, Arbortext Styler highlights the base element from which the specialized element is getting its style.
Arbortext Styler user interface - Arbortext Styler recognizes when an unstyled specialized element has an associated base element that has been styled and provides that information in the Elements list.
For example, the DITA step element is a specialization of the li element. If you have styled li but not step, Arbortext Styler applies the styling for the li element and displays the following message in the Elements list for the step element:
Unstyled (List Item by specialization)
If you hover the cursor over this message, the following additional information is provided in a small popup (tooltip):
(Specialization of li, using List Item style)
Publishing - When publishing with an Arbortext Styler stylesheet, the publishing process replaces unstyled, specialized elements with the associated base element.
Arbortext Styler preview - Arbortext Styler replaces unstyled, specialized elements with the associated base element in preview operations.
Note that once you style a specialization of an element that is styled as a division, it is no longer associated with the base element for division numbering. This is because Arbortext Styler counts an unstyled, specialized element along with its base element, but counts a styled, specialization separately from its base element. For this and similar reasons, it is often a good practice to leave specialized elements unstyled and allow the fallback processing to apply styling.