Junctors are wired from LLF through the junctor grouping frame to the levels of trunk junctor switches in the trunk link frame (TLF). Unlike earlier designs, the junctors have no supervisory relays or other active hardware, all such functions being assigned to trunk circuits. The basic design of the TLF has ten junctor switches with their horizontal multiples split in half, hence two hundred junctors, and two hundred trunk links to the ten trunk switches. The banjo wiring of the trunk switch was not split, but a discriminator level trick devoted two levels to doubling the use of the other eight, thus allowing each trunk switch to connect sixteen trunks to its twenty trunk links. This results in the TLF having a 0.8:1 trunk concentration ratio (TCR). This degree of deconcentration eventually turned out to provide too few trunk appearances for the variety of trunk types needed. The final 1970s 5XB offices had type C trunk switches with twelve levels, using two for discrimination, leaving a TCR of unity.