finally the computation of the particle masses and some mixing angles.

Many phenomenological analyses of the model have appeared before [@Ellis; @ERS1; @King; @King2; @ERS2]. The purpose of the present work is twofold. First, we implement the most recent experimental constraints on sparticles, Higgs and top quark masses from the LEP and the Tevatron [@PDG; @Aleph]. Second, we explain the results of our numerical procedure with the help of analytic approximations and inequalities among the parameters. Once the vacua which break colour, electromagnetism or correspond to $\tan \beta
=\infty$ are forbidden and the experimental constraints are imposed, these formulae allow us to understand the essential features of the bounds on and correlations among some particle masses. Quite a lot of attention is paid to the property found in [@ERS1], namely, that the singlet scalar acquires a v.e.v. which is much larger than the Higgs ones. Indeed, this has the important consequence that the singlet fermion and scalars quite decouple from the the other multiplets as already mentioned.

In section \[sec:properties\] we review the motivations for the model, its essential differences with respect to the MSSM due to the enlargement of Higgs sector and the status of the spontaneous CP violation. 