There are two types of elements discussed here: top-level elements and instructions. A top-level element must appear as the child of either
<xsl:transform>. An instruction, on the other hand, is associated with a template. A stylesheet may include several templates. A third type of element, not discussed here, is the literal result element (LRE). An LRE also appears in a template. It consists of any non-instruction element that should be copied as-is to the result document, for example, an
<hr> element in an HTML conversion stylesheet.
On a related note, any attribute in an LRE and some attributes of a limited number of XSLT elements can also include what is known as an attribute value template. An attribute value template is a string that includes an embedded XPath expression which is used to specify the value of an attribute. At run-time the expression is evaluated and the result of the evaluation is substituted for the XPath expression. For example, assume that a variable "
image-dir" is defined as follows:
The expression to be evaluated is placed inside curly brackets:
This would result in the following:
The element annotations that follow include a description, a syntax listing, a list of required and optional attributes, a description of type and position, its source in the W3C Recommendation and an explanation of the degree of present Gecko support.