This optional parameter acts as a label that can be useful for
custom code in hooks. It can also be referred to by <Log xxxxxx> in
any other clause.
<AuthBy whatever>
# With an Identifier, can refer to this logger from
# other clauses
<Log SQL>
Identifier mylogger
DBSource xxxxxx
....
</Log>
....
</AuthBy>
<AuthBy whatever>
# This AuthBy will log to the Log SQL above
Log mylogger
.....
</AuthBy>