The free movement of people in a flow is a special case of the movement of human flows in buildings, constructions and in the territory of their complexes. Here the fullest manifestation of individual qualities of each person that defines probability of values of parameters of their movement is possible. They don't depend on influence of density of a human flow. The given provisions and probabilistic methods of modeling of the free movement of people give objective initial criteria of a correctness of individual and line models and the programs realizing them. As in the absence of influence of density of distribution of people on length of a way and time of their arrival to its concrete section are functions of casual argument - speeds of the movement of people, any individual and line model has to correspond at the free movement to well-known methods of probability theory. Check of individual and line model on compliance to these methods is paramount criterion of its correctness. Without performance of this criterion further consideration of any individual and line model, as if it didn't imitate influence of density of a stream on the movement of people, loses meaning.