  A class of k-particle observables in a two-mode system of Bose particles is
characterized by typicality: if the state of the system is sampled out of a
suitable ensemble, an experimental measurement of that observable yields
(almost) always the same result. We investigate the general features of typical
observables, the criteria to determine typicality and finally focus on the case
of density correlation functions, which are related to spatial distribution of
particles and interference.
