Re: operator new: reconciling sections 18.4 and 5.3.4(13) of the 2003 standard

Operator new as defined in Section 18.4 of the 2003 edition is as
follows:

  void *operator new (size_t) throw
(std::bad_alloc); ///1
  void *operator new[] (size_t) throw
(std::bad_alloc); ///2
  void *operator new (size_t, const std::nothrow_t&)
throw(); ///3
  void *operator new[] (size_t, const std::nothrow_t&)
throw(); ///4

Yet 5.3.4(13) states:

[unless an allocation function is declared with an
empty-exception specification (15.4), throw(), it indicates
failure to allocate storage by throwing a bad_alloc exception
(clause 15, 18.4.2.1); it returns a non-null pointer
otherwise. If the allocation function is declared with an
empty exception-specification, throw(), it returns null to
indicate failure to allocate storage and a non-null pointer
otherwise. ]

Two questions:
a) Does the reference to 'allocation function is declared with an
empty-exception specification (15.4), throw()' imply items '///3' and
'///4' as shown above?

b) I'm under the impression that section 18.4 is binding, that
said, if I provide overriding definitions then those those
definitions ought to comply with 18.4. True or False?