4.1.5 Function Calls

Norm

"Each argument expression in a function call is normalized to its
corresponding Core expression by applying []_FunctionArgument(Type)
for each argument with the expected SequenceType for the argument
inserted."
    Delete "for each argument"; it's redundant.
    s/SequenceType/Type/
    Change "with the expected SequenceType for the argument inserted"
    to "where Type is the corresponding parameter type".

Norm / rule 1 / conclusion
    The '==' and the following line are leftovers. Delete them.

"Note that this normalization rule depends on the function signatures,
which is used to get the types of the function parameters
(SequenceType1,...,SequenceTypen)"
    s/signatures/signature (found in statEnv.funcType)/
    s/SequenceType/Type/g

"For user-defined functions, the function signature can be obtained from
the XQuery prolog where the function is declared. For built-in functions,
the signature is given in the [Functions and Operators] document."
    No, the signatures can be obtained from the static environment
    (specifically, statEnv.funcType). They are *derived* from declarations
    that appear elsewhere, which is maybe what you meant.

"For overloaded built-in functions, several signatures may exists,
however, because they all correspond to sequences of atomic values, they
all result in the same normalization."
    This sentence is irrelevant/meaningless, because calls to overloaded
    built-in functions cannot occur in non-Core queries, and thus are not
    subject to the preceding normalization rule.
    (It's a leftover, delete it.)