maximum levels of hierarchy
Example of moduleName/counterHierarchy:
switch/00:00:00:00:01:02:03:04/pktin/drops where
moduleName ==> "switch" and
counterHierarchy of 3 ==> "00:00:00:00:01:02:03:04/pktin/drops"
Note the true minimum length for this header is 8 including a pad to 64
bit alignment, however as this base class is used for demuxing an
incoming Action, it is only necessary to read the first 4 bytes.