A Multi-level Process Map is created when a Drill Down is added to an Activity in the Process Map
A Multi-level Process Map is created when a Drill Down is added to an Activity in the Process Map, linking to another Process Map, creating new levels to the Process Map. When a map is created initially, it is mapped on one level. When add a Drill Down to that map, you add another level to that map, below the base level.
The levels of the map are usually numbered from 1 at the highest level and count upwards through 2, 3, 4 at each newly created lower level.
Typically Process Maps have no more than six levels, as this is generally enough to capture the full detail required.
Drilldowns allow you to navigate around a multi-level process map, you can add them to Activity shapes enabling you to open a link to another map.