From Bell System Practice 359-200-500, issue 2, p. 6, as published in "CAPAR IV: L4-L5 Carrier", AT&T Long Lines, Eastern Area, 1977
From Bell System Practice 359-200-500, issue 2, p. 6, as published in "CAPAR IV: L4-L5 Carrier", AT&T Long Lines, Eastern Area, 1977