The full XSL language logically consists of three component languages
which are described in three W3C (World Wide Web Consortium) Recommendations:
XPath: XML Path Language--a language for referencing specific parts
of an XML document
XSLT: XSL Transformations--a language for describing how to transform
one XML document (represented as a tree) into another
XSL: Extensible Stylesheet Language--XSLT plus a description of
a set of Formatting Objects and Formatting Properties
XML to result tree
An XSLT "stylesheet" transforms the input (source) document's tree into a structure called a
result tree consisting of result objects.
Result tree doctypes
The result tree's structure is that of an XML document, and its objects
correspond to elements with attributes
The result tree's structure and "tag set" can match that
of any XML document or doctype. In particular, the result tree could be:
HTML/XHTML
result tree is easily written out as an HTML document
other XML doctype
result tree is easily written out as an
XML document in this other doctype (for some further application-specific
processing)
FO result tree
result tree's structure (and element and attribute
names) matches the set of formatting objects and formatting properties
defined by the (non-transformation) part of XSL
Serialization of the result tree is not necessary for further processing
of the result tree.
An XSL stylesheet
An XSL stylesheet basically consists of a set of templates
Each template "matches" some set of elements in the source tree and
then describes the contribution that the matched element makes to the result
tree
Generally, elements in a stylesheet in the "xsl" namespace are part
of the XSLT language, and non-xsl elements within a template are what get
put into the result tree
HTML vs. XSL Formatting Objects
Transformation is independent of the target result type
Most people are more familiar with HTML so many of the examples
in this tutorial use HTML
The XSL implementation in IE5 is incomplete.
The examples in this tutorial will not work in IE5
The techniques apply equally well to XSL Formatting Objects
or other tag sets
XSLT is a tree-to-tree transformation process
Serialization may vary depending on the selected output method
There is a distinction between HTML element names and HTML
The Structure of a Stylesheet
XSLT Stylesheets are XML documents; namespaces (http://www.w3.org/TR/REC-xml-names)
are used to identify semantically significant elements.
Most stylesheets are stand-alone documents rooted at <xsl:stylesheet>
or <xsl:transform>. It is possible to have "single template"
stylesheet/documents.
<xsl:stylesheet> and <xsl:transform> are completely
synonymous.
Note that it is the mapping from namespace abbreviation to URI that
is important, not the literal namespace abbreviation "xsl:" that
is used most commonly.
