log-files: Initial two Char?

[Carl Schreiber]

Does anybody know what are the meanings of the initial two char. of the log-files:

DO, MG, RQ, RH, CG, HN, RF, OM, DQ, IS, CR, LQ, MP, OL, DE, EK, ER, HS, IO, KF, KE, JL, ...

Is it somewhere documented?

[Stanislav Korotky]

This is a check sum calculated on the log content, so MQ can be sure that sended/posted fragments are not altered (intentionally) somehow and produced directly by the terminal.