managed vs. explicitly_managed

We are setting interfaces and ports to managed/unmanaged using a perl script, using object->manage() or object->setManagedState().

I was playing a bit with the various ways, but couldn't find out exactly how explicitly_(un)managed differs from (un)managed. Seemingly explicit states are overwritten only by another explicit state.

Is changing states working that way?

How could I go back to the "default" behaviour  (eg. uplink ports are managed, access ports are unmanaged by default)? 

Regards,

Gunter