XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (292 page)

Within XML text nodes, apostrophes and quotation marks can be written literally without escaping—there is no need to use the entity references
'
and
"
.

I find it quite useful to have two global variables available in a stylesheet, as follows:

This makes it possible to use the variables
$apos
and
$quot
to construct strings using the
concat()
function, for example:

Names

Names are used within an XPath expression to refer to elements and attributes in a source document, and to refer to objects such as variables, functions, and types.

Expression	Lexical Rules
QName	(Prefix : )? LocalPart
Prefix	NCName
LocalPart	NCName
NCName	(Letter | _ ) (NCNameChar) *
NCNameChar	Letter | Digit | . | - | _ | CombiningChar | Extender