Reports the name of an element or an attribute that is used in an XPath-expression but is missing in the associated XML file and is not defined in the referenced schema. This prevents problems caused by typos in XPath-expressions that otherwise occur when running the script and may even happen not to be recognized immediately.

Example:

<xsl:template match="h:txtarea" />

If the h is bound to the XHTML namespace, the inspection will report this part of the match expression as an unknown element name because the correct name of the element is "textarea".