Return the decimal format Symbols for this element.
The xsl:decimal-format element declares a decimal-format,
which controls the interpretation of a format pattern used by
the format-number function. If there is a name attribute, then
the element declares a named decimal-format; otherwise, it
declares the default decimal-format. The value of the name
attribute is a QName, which is expanded as described in [2.4 Qualified Names].
It is an error to declare either the default decimal-format or a
decimal-format with a given name more than once (even with different
import precedence), unless it is declared every time with the same
value for all attributes (taking into account any default values).
The other attributes on xsl:decimal-format correspond to the
methods on the JDK 1.1 DecimalFormatSymbols class. For each get/set
method pair there is an attribute defined for the xsl:decimal-format
element.