The xsl:attribute-set element is used to declare a named collection of attributes, which will often
be used together to define an output style. It is declared at the top level (subordinate to xsl:stylesheet).
An attribute-set contains a collection of xsl:attribute elements.
The attributes in an attribute-set can be used in several ways:
They can be added to a literal result element by specifying xsl:use-attribute-sets in the list of attributes
for the element. The value is a space-separated list of attribute-set names. Attributes specified explicitly on
the literal result element, or added using xsl:attribute, override any that are specified in the attribute-set
definition.
They can be added to an element created using xsl:element, by specifying use-attribute-sets in the list of attributes
for the xsl:element element. The value is a space-separated list of attribute-set names. Attributes specified explicitly on
the literal result element, or added using xsl:attribute, override any that are specified in the attribute-set
definition.
One attribute set can be based on another by specifying use-attribute-sets in the list of attributes
for the xsl:attribute-set element. Again, attributes defined explicitly in the attribute set override any that
are included implicitly from another attribute set.
Attribute sets named in the xsl:use-attribute-sets or use-attribute-sets attribute
are applied in the order given: if the same attribute is generated more than once, the later value always takes
precedence.
