This paper introduces a method to analyse the self-framing properties of mBnB line codes. Consideration of correlation in the received bit stream yields a three step analysis technique: (1) evaluation of the probability that any n-bit sequence in the received bit stream simulates a codeword, (2) development of a mathematical description of the desired lock entry and lock exit algorithms, and (3) the derivation and evaluation of equations which give framing performance for the frame search strategy of interest. Following discussion of the analysis technique, the framing performance of a 7B8B code is investigated. The results of the analysis are compared with those obtained by simulation to confirm the validity of the analysis technique.