normalize-space and sequence

Hello,

  I am having a very simple issue here. I'd like to be able to apply
normalize-space() even if I am dealing with a sequence of string. If I
do call normalize-space, the transformation implicitly convert my
sequence of string into string (saxon 8.9).
  What's is this function that convert sequence of strings into string ?

  As a side note, there is no way to globally say 'all my xml
attribute/elements should have normalize space'.

Thanks,

-- 
Mathieu