Line build out (LBO) is loss inserted by the CSU in order to meet the 15 to 22.5 dB loss requirement of the premises remote-end section. Selected so that (phone company loss) + (cable length loss) + (line build out) is greater that 15dB but less than 22.5 dB. buildOut0 means insert 0 dB. buildOut7p5 means insert 7.5 dB. buildOut15 means insert 15 dB.