We consider the breaking of the grand unification group SO(10) to the
standard model gauge group through several chains containing two intermediate
stages. Using the values of the gauge coupling constants at scale MZ derived
from recent LEP data, we determine the range of their intermediate and
unification scales. In particular, we identify those chains that permit new
gauge structure at relatively low energy (∼1TeV).Comment: (LATEX, 9 pages + 3 pages of figures not included) OITS-48