changes in XQuery and SPARQL's use of XQuery

XQuery, XPath, and XPath F&O have changed in a number of ways since I
used them to draft the original Invocation and Effective Boolean Value
sections.
  - XQuery now has an additional type of promotion, conversion of
    xsd:untypedAtomic to the expected type for a function, (xsd:double
    for numeric arguments).
  - XQuery now has an additional type of promotion, URI promotion which
    converts xsd:anyURI to xsd:string when the latter is needed.
  - If the argument is a typed literal with a datatype of xsd:boolean or
    a derived from xsd:boolean, the EBV (effective boolean value) is the
    truth value of argument.
  - EBV rules for xsd:string apply to types derived from xsd:string.

SPARQL supports only string, double, float, integer, and
dateTime. Conspicuously absent from this list is xsd:boolean, however,
it appears in several places in the spec. I propose that, in the
interest of editorial simplicity and compatibility with XQuery, we add
xsd:boolean to the set of supported datatypes. [Note to self, uncomment
the @@s to add xsd:boolean.]

Also, our use of plain literal may be closer to XPath's use of
xsd:untypedAtomic than to xsd:xstring. Needs more thought. Related
thread:
  http://lists.w3.org/Archives/Public/public-rdf-dawg/2005OctDec/thread#230

SPARQL issues text:
  http://www.w3.org/2001/sw/DataAccess/rq23/#invocation
  http://www.w3.org/2001/sw/DataAccess/rq23/#ebv

Some XQuery et al evaluation notes:
  http://www.w3.org/2005/11/XQueryTour/
-- 
-eric

office: +81.466.49.1170 W3C, Keio Research Institute at SFC,
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