XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (351 page)

BOOK: XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition

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Data type	Definition of ordering
xs:string or xs:anyURI	An xs:anyURI value is treated as a string. The ordering of strings is determined by a collation, in the same way as equality comparison. These operators use the default collation established in the XPath evaluation context, as described in Chapter 7. There's a tension between equality comparison and ordering comparisons: for testing equality, you often want a weak collation; for example, one that compares yes and YES as equal. But for ordering, you often want to put the strings in some kind of order, even if it's fairly arbitrary, so you want yes either to be less than YES , or greater than it (that is, you want a strong collation). If you want to use different collations for different operations, you can achieve this by using the compare() function described in Chapter 13, but for the eq and lt family of operators, you have to choose a single collation that may be a compromise.
Numeric	Any two numeric values can be compared ( xs:integer , xs:decimal , xs:float , or xs:double ). If they are of different types, one value is first promoted to the type of the other in the same way as arithmetic operators (see page 571). They are then tested for numeric order (this means, for example, that 10 is greater than 2 ).