About Arbortext Styler > Arbortext Styler Dialog Boxes > XPath Predicate Dialog Box
XPath Predicate Dialog Box
The XPath Predicate dialog box displays when you select XPath Predicate from the Position list in the Context dialog box. Use this dialog box to create or edit an XPath predicate.
Type the XPath predicate in the text box. Use valid XPath predicate syntax, omitting the square brackets surrounding the predicate as these are applied automatically by Arbortext Styler.
The read-only Context field shows the context for which the predicate is being written
If you enter the name of a namespaced element in this field, you will not be prompted to declare the namespace if it does not already exist. Ensure you have declared the namespace for the stylesheet by creating an element with the applicable prefix, or the XPath expression you enter in this field will not be valid
With DITA document types, predicates should only be attached to the element defined by the context. The use of general contexts such as image anywhere in topic[@outputclass=’tpdr’] should be avoided. They will not work in Edit view, and Arbortext Styler will not indicate that the context matches when you position the cursor in the edit window inside an element that should match. They will also not match in print/PDF output generated by the FOSI print engine.
Instead, use a context such as image[ancestor::topic/@outputclass=’tpdr’].
You must understand XPath and its syntax to use this option. Refer to the World Wide Web Consortium (W3C) web site (www.w3.org/TR/xpath) for information on the XPath standard.
The use of certain XPath expressions can cause increased processing times. Please refer to XPath Performance for information and suggested alternatives.