XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (812 page)

Pattern (XSLT)

A construct that defines a condition that a
node
either satisfies or does not satisfy. The syntax for a pattern is a subset of the syntax for an XPath
expression
. Patterns are used in only four XSLT elements:

,

,

, and

.

Precedence (XSLT)

See
Import Precedence
.

Preceding Axis (XPath)

The preceding
axis
selects all the
nodes
that precede the
context node
within the same
tree
, with the exception of
attribute
and
namespace
nodes, and the node's own
ancestors
. This is a
reverse axis
.

Preceding Sibling Axis (XPath)

The preceding sibling
axis
selects all the
nodes
that precede the
context node
and that share the same parent node. This is a
reverse axis
.

Predicate (XPath)

An
expression
used to filter which
nodes
are selected by a particular
step
in a
path expression
or to select a subset of the
items
in a
sequence
. A boolean expression selects the items for which the predicate is true; a numeric expression selects the item at the position given by the value of the expression, for example
[1]
selects the first item.

Prefix (XML Namespaces)

See
Namespace Prefix
.

Primitive Type (Schema)

The XML Schema specification defines 19 primitive types. In the XPath model these are defined as subtypes of the abstract type
xs:anyAtomicType
, which contains all atomic values. The 19 primitive types are
boolean
,
string
,
decimal
,
double
,
float
,
QName
,
anyURI
,
hexBinary
,
base64Binary
,
date
,
time
,
dateTime
,
gYear
,
gYearMonth
,
gMonth
,
gMonthDay
,
gDay
,
duration
, and
NOTATION
. XPath in effect adds
untypedAtomic
to this list, representing values that have not been
validated
against any
schema
.

Principal Node Kind (XPath)

Every
axis
has a principal
node kind
. For most axes, the principal node kind is
elements
. For the
attribute axis
, the principal node kind is
attribute
, and for the
namespace axis
, it is
namespace
. The principal node kind determines the kind of nodes selected by the node test
*
; for example,
following-siblings::*
selects elements, while
namespace::*
selects
namespace nodes
.

Priority (XSLT)

Every
template rule
has a priority. The priority is expressed as a number (which may be a decimal number such as
3.5
). The priority may be specified explicitly, using the
priority
attribute of the

element; if it is omitted a default priority is allocated based on the
pattern
. The priority is used to decide which
template rule
to evaluate when several template rules match the same
node
: a rule with numerically higher priority is used in preference to one with lower priority.

Processing Instruction (XML)

An item in an XML
document
that is conventionally used to carry instructions to the software that receives the document and processes it. Written between the delimiters
?
and
?
. Note that the XML declaration at the start of a document, and the text declaration at the start of an external parsed entity, are not processing instructions even though they use the same delimiters.