XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (567 page)

Changes in 2.0

In XSLT 1.0, the effect of the function was defined by reference to the Java JDK 1.1 specifications. This created problems because the JDK 1.1 description left many details underspecified, and later versions of the JDK not only clarified the specification, but also added new features. It was therefore decided in XSLT 2.0 to provide a freestanding definition of this function. This is largely compatible with the old JDK 1.1 specification, but the rules are now much more precise, and in corner cases they will not necessarily give the same results as implementations based on the JDK, let alone non-Java implementations. For example, the JDK 1.1 specification did not say how rounding was done. The actual JDK 1.1 implementation used the rule of rounding a final 5 to the nearest even number, and this is the rule that XSLT 2.0 has adopted, but XSLT 1.0 processors might well do rounding differently.

Signature

Effect

The function returns a string value; this is the result of formatting the given
value
using the format picture supplied in
picture
, while applying the rules defined in the decimal format named in
format
if present, or using the default decimal format otherwise.

The decimal-format Name

The
format
argument, if it is present, must take the form of a lexical
QName
; that is, an XML name optionally prefixed with a namespace prefix that corresponds to a namespace declaration that is in scope at the point in the stylesheet where the
format-number()
function is called. There must be an

element in the stylesheet with the same expanded name, using the namespace URIs rather than prefixes in the comparison.

If the
format
argument is omitted, the default decimal format is used. A default decimal format can be established for a stylesheet by including an

element with no name. If there is no unnamed

element in the stylesheet, the system uses a built-in default format, which is the same as specifying an

with no attributes.

The Picture String

The structure of the
picture
string is as follows. Here, and in the text that follows, I will use the default characters for each role: for example
;
as the pattern separator,
.
as the decimal point,
0
as the zero digit,
#
as the optional digit placemarker, and so on. Remember, though, that you can change the characters that are used in each of these roles using the

declaration.

Construct	Content
picture	subpicture ( ; subpicture)?
subpicture	prefix? integer ( . fraction)? suffix?
prefix	Any characters except special characters
suffix	Any characters except special characters
integer	# * 0 * (but also allowing , to appear)
fraction	0 * # * (but also allowing , to appear)