jcr:score(...) as xs:decimal
As described in 6.6.3.1 Column Specifier, a score value is returned for each row the result table. However, how this value is calculated is left up to the implementation. It is not required that its contents always be meaningful.
The XPath function jcr:score(...) is provided to enable queries to specify score calculation parameters in those implementations that support it.
The jcr:score(...) function must therefore be supported, but the number and meaning of its parameters is left up to the implementation. The jcr:score(...) function can be used in either the columns specifier of the query, or the order specifier. It is also possible (though not required) that implementations support multiple jcr:score(...) functions within a single query.
The column within which the score information is returned may be labeled simply jcr:score or it may be labeled with the signature and parameters of the jcr:score(...) function used. Additional score-related columns may be also returned by implementations that support multiple jcr:score(...) functions with varying parameters (see 8.5.2.4 Pseudo-property, 6.6.5.2 jcr:contains Function, and 8.5.4.5 CONTAINS).
Support for comparing jcr:score(...) in a predicate is not required.