  I discuss Haldane's concept of generalised exclusion statistics (Phys. Rev.
Lett. {\bf 67}, 937, 1991) and I show that it leads to inconsistencies in the
calculation of the particle distribution that maximizes the partition function.
These inconsistencies appear when mutual exclusion statistics is manifested
between different subspecies of particles in the system. In order to eliminate
these inconsistencies, I introduce new mutual exclusion statistics parameters,
which are proportional to the dimension of the Hilbert sub-space on which they
act. These new definitions lead to properly defined particle distributions and
thermodynamic properties. In another paper (arXiv:0710.0728) I show that
fractional exclusion statistics manifested in general systems with interaction
have these, physically consistent, statistics parameters.
