lprng and apsfilter: where's the log?

According to the commentary in apsfilter, the log produced by tracing with "set -x" shows up in "/var/spool/lpd/*/log": # For debugging --- see for stderr in /var/spool/lpd/*/log However, all the relevant log files are still empty after I've turned on debugging and printed a file. This happens with lprng; with lprold, the log file does have the expected output. Anyone know where the log file, or any other output on standard error, can be found? Paul