To compile the "gold" (not known to be faulty) version of concordance:
Compile using g++ with no -D switches.

To compile faulty version XX:
Compile using g++ with the switch -DFAULTXX .
(XX can be anything from 01 to 13, but must be 2 digits.)
Each faulty version represents one real fault that was found in the
original concordance program.

To compile using multiple faults, use multiple -D switches.

To compile the original version of concordance as found on the Internet,
turn on all 13 faults.

