  A non-binary (2,v)-regular LDPC code is defined by a parity-check matrix with
column weight 2 and row weight v. In this report, we give an ontology-based
approach to the optimization for this class of codes. All possible
inter-connected cycle patterns that lead to low symbol-weight codewords are
identified to put together the ontology. The optimization goal is to improve
the distance property of equivalent binary images. Using the proposed method,
the estimation and optimization of bit-distance spectrum becomes easily
handleable. Three codes in the CCSDS recommendation are analyzed and several
codes with good minimum bit-distance are designed.
