3.5.3 SequenceType Syntax

"Normalization of SequenceTypes is the only example of normalization that
does not yield an expression in the [XPath/XQuery] Core"
    Well, there are a few normalization rules that don't yield
    *expressions*, although they do yield constructs in the Core:
        []_Case []_Param []_PrologDecl
        []_ArithOp/ValueOp/GeneralOp/OverloadedOp
    And there's also []_Schema (and all its subordinates), which yields
    Formal Definitions, although maybe you don't count that as
    normalization.