Actually, that is incorrect, there is code to support it but it was originally incorrect as Raghavendra pointed out above in that it is based on a historic misalignment between QPLAN_* and enum_slow_log_filter. This seems to have been fixed by Laurynas in 02/2013 and this bug was never marked as fixed. There are test cases for these now in t/percona_log_slow_query_plan.test.
Actually, that is incorrect, there is code to support it but it was originally incorrect as Raghavendra pointed out above in that it is based on a historic misalignment between QPLAN_* and enum_slow_ log_filter. This seems to have been fixed by Laurynas in 02/2013 and this bug was never marked as fixed. There are test cases for these now in t/percona_ log_slow_ query_plan. test.