Regular expression /s whitespace : Which whitespace?

I am using count(tokenize(lower-case(.),'(\s|[,.!:;])+')[string(.)]) -a technique I retrieved from the list for counting words. I have been questioned about the regular expression that is being used to find white spaces. The content can contain many kinds of whitespaces and i am being asked to defend using this expression to find words. Does the saxon 8b interpretation of this regular expression covers as whitespaces
 
--------------------Karen McAdams