  In Gepner's pioneering work, the requirement that leads to a model having the
desired $N=1$ Spacetime supersymmetry and $E(8)\times E(6)$ Gauge symmetry was
the requirement that the spacetime symmetry is compatible with modular
invariance. In this work we show that the requirement for the simultaneous
fulfillment of mutual locality of the left-moving vertices of physical states
with the space-time symmetry generators and of right-moving vertices with
generators of $E(8)\times E(6)$-gauge symmetry, which arises after some special
reduction together with the requirement of mutual locality of complete
(left-right) vertices of physical states among themselves leads to the same
Gepner models.
