  Zipper codes with irregular variable degree are studied. Two new interleaver
maps -- chevron and half-chevron -- are described. Simulation results with
shortened double-error-correcting Bose--Chaudhuri--Hocquenghem constituent
codes show that zipper codes with chevron and half-chevron interleaver maps
outperform staircase codes when the rate is below 0.86 and 0.91, respectively,
at $10^{-8}$ output bit error rate operating point. In the miscorrection-free
decoding scheme, both zipper codes with chevron and half-chevron interleaver
maps outperform staircase codes. However, constituent decoder miscorrections
induce additional performance gaps.
