[xsl] Creating XPath2 functions:passing a set of nodes, what is the signature construction?

[cknell@xxxxxxxxxx]

I am learning XPath2 using Saxon 8.6. I'd like to create a funtion to compute the standard deviation of the value of a set of nodes. Is there some special way to construct the signature of the function when the argument is a set of nodes as opposed to a single node?

I have written a funtion that takes a single node as an argument of type xs:double. Is there some special way to state that the function will take a set of nodes of type xs:double, or do I simply state that the argument will be of type xs:double?

-- 
Charles Knell
cknell@xxxxxxxxxx - email