RE: [FO] fn:substring arguments

> What is the motivation for the F&O spec to define the 
> startingLoc argument as, xs:double and not an integer?

Primarily backwards compatibility: XPath 1.0 only had one numeric data type,
which was equivalent to xs:double in XPath 2.0. If it had been defined as
xs:integer, then valid XPath 1.0 expressions such as

substring($s, 1, (string-length($s) div 2))

would have been rejected as errors in XPath 2.0.

Michael Kay
http://www.saxonica.com/