4.1.5 Function calls
Under "Notations", the three definitions of mappings would be
more readable if you adopted the convention of placing the
"if" statement before the value rather than after the value.
Thus the first one would be rewritten:

[Expr]atomicAtomize(SequenceType) denotes

  if SequenceType <: xdt:anyAtomic* and ...
  then fn:data(Expr)
  else Expr