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XSLT/XPATH jargon


Subject: XSLT/XPATH jargon
From: "Pawson, David" <DPawson@xxxxxxxxxxx>
Date: Thu, 20 Jan 2000 12:13:50 -0000

RTF and AVT finally did it.

I've 'lifted' various definitions from various places to try and put
together
a jargon buster for XSLT.  Comments please prior to my putting it in
the FAQ.
What would you like in it / whats missing.
Can you improve on the definitions?
I'd appreciate any help.

Intent is clarity of understanding, not exactness.

Regards, DaveP




XSLT Terminology:
Source: W3C Recommendation 16 November 1999
Revision: Draft 0.a

@: The @ character is an abbreviation for the attribute:: axis. 

.. : The string .. is an abbreviation for parent::node(). 


* : A * matches all of the element children of the context node.

. : The . character is an abbreviation for self::node(). 

/ : the / character at the start of a location path makes it
absolute, i.e. starting at the root node of a document.


// : The string // is an abbreviation for descendant-or-self::node(). 

ATTRIBUTE VALUE TEMPLATE: An expression can be used by
surrounding the expression with curly braces ({}). The
attribute value template is instantiated by replacing the
expression together with surrounding curly braces by the
result of evaluating the expression and converting the
resulting object to a string as if by a call to the string
function.  Plain English version please someone????


AXIS: There are 13 axes defined in XPath:

child, descendant, parent, ancestor, following-sibling,
preceding-sibling, following, following, preceding,
attribute, namespace, descendant-or-self,
ancestor-or-self. Each specifies a 'direction' relative to
the context node and can be used to provide an initial
selection of nodes.


CONTEXT NODE:
The context node is where XPATH addressing starts. 


CURRENT NODE: When a template is instantiated, it is always
instantiated with respect to a current node and a current
node list. Plain English version please??

DOCUMENT ORDER: Normally top down, left to right traversal
of the document tree. The ancestor and preceding axes use
reverse document order and the attribute and namespace axes
are unordered. If parentheses are used for grouping, you
will always get forward document order.

EXPRESSION: Expressions are used in XSLT for a variety of
purposes including:

selecting nodes for processing; 
specifying conditions for different ways of processing a node; 
generating text to be inserted in the result tree. 

 
LOCATION PATH: There are two kinds of location path:
relative location paths and absolute location paths. A
location path describes how a specific part of a document
may be found. Location paths describe the address of one
node with respect to another. A location path is composed of
a series of steps. Each step consists of an axis, a node
test and optional predicates . The syntax for a location
step is the axis name and node test separated by a double
colon, followed by zero or more expressions each in square
brackets. For example, in child::para[position()=1], child
is the name of the axis, para is the node test and
[position()=1] is a predicate.

NODE TEST: A node test identifies a type of node in the
document, the simplest type being an element name.

NODE TYPE: There are seven node types: element, attribute,
text, processing instruction, comment, namespace, and
root. These are: the elements, attributes, text, processing
instructions, and comments in a document. Namespace nodes
represent the namespaces used in the document. The root node
is the root of the document. In every XML document, there is
exactly one root node, which the node that contains the
(optional) prologue and the document element.


PREDICATE: A predicate occurs in square brackets after the a
node test. For example, para selects all of the para
children of the context node. Adding the predicate [3]:
para[3] selects only the third para element.  XPATH section
4 and XSLT section 12 enumerate all the functions.

ROOT NODE: The root node is the root of the document tree.

RESULT TREE FRAGMENT: Some part of the output resulting from
triggering a template.


RTF: See Result Tree Fragment



STEP: Steps may be joined with slashes to form a complete
location path.

XPATH: XPath is a language that describes how to locate
specific elements (and attributes, processing instructions,
etc.) in a document. It allows you to locate specific
content within an XML document. XPATH treats an XML document
as a logical ordered tree,


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