c. Make certain that minimum required receiver-to-receiver
separations are maintained at all sites where two or more receivers
are located; in this case it would be the three relays that would
have to be checked for proper receiver-to-receiver separation.
this reason, frequencies from a specific block may not always be
d. The two-block plan can be used for a simple parallel system.
Tangent systems from any site in a parallel system to other sites may
be established. This is possible because from any site in a parallel
system, all transmitter frequencies are from one block and the
distant station could transmit on the opposite block. The two-block
plan does not provide for alternate routing or operating between
three different sites.
When networks become too complex, then
another plan should be used and that is the six-block ABM plan.