Diplomacy: Theory and Practice, 5th ed. – Online updating pages
Chapter 16: Special Missions
p. 242, lines 11-12 down, ‘permits flexibility’: Murty (see Further reading below) explains this point more fully, noting that the great variety of special missions that I proceed to talk about was an important reason for the wise decision reflected in the New York Convention ‘not to provide the same peremptory prescriptions with respect to all missions’ (p. 263). In fact, most of the Convention’s provisions were given a ‘residual character’ – they were a set of model rules (we might say ‘best practice’) that might be imported into an agreement on the despatch of a special mission or become operative in the absence of any such agreement. Fortunately, the section on special missions appears in the publisher’s preview of Murty’s book on the Internet.
Further reading: additions and links
Murty, B. S., The Diplomatic Instrument and World Public Order (New Haven and Nijhoff, 1989), pp. 262-6
Kalb, Nadia, ‘Immunities, Special Missions’, in Max Planck Encyclopedia of Public International Law
Wood, Michael, ‘The Immunity of Official Visitors’, Max Planck UNYB 16 (2012)