ique, these circuits need no conditioning; they are full-load sections (i.e., D/2 + D/2 = 1D, a full- load section). Meanwhile, the 50 circuits entering from each direction are terminated for Planning period refers to telecommunication planning. Here we mean advanced planning for growth. Planning periods may be 5, 10, or 15 years in advance of an installation date. 8Main frame. This is a facility, often a frame at a switching center, where all circuits terminate and where they may be cross-connected. In other words, this is a location where we can get physical or virtual access to a circuit and where we may reconfigure assets. Main frames in local serving switches often are extremely large, where 10,000 or more subscriber lines terminate. 5.6 VF REPEATERS (AMPLIFIERS) Loaded VF cable Exchange Exchange Exchange Figure 5.5 Loading of VF trunks (junctions). switching and need conditioning SO that each looks electrically like a full-load section. However, the physical distance from the switch out to the first load point is D/2 or, in the case of H loading, 3000 ft or 915 m. To make the load coil distance electrically equivalent to 6000 ft or 1830 m, line build-out (LBO) is used. LBO is described in Section 5.5.2.1. Suppose that the location of a new switching center was such that it was not halfway, but at some other fractional distance. For the section comprising the shorter distance, LBO is used. For the other, longer run, often a half-load coil is installed at the switching center and LBO is added to trim up the remaining electrical distance. 5.5.2.1 Line Build-Out (LBO). In many instances the first (and last) load coil cannot be placed at a D/2 distance from a switch or the separation between load coils cannot be D within tolerance. The reasons for the inability of an installation crew to meet the siting requirements are varied. Buildings could be in the way; the right-of-way required a detour; hostile cable ground conditions exist; and SO forth. In these cases, we install the load coil at a distance less than D/