When using the dgInfo command to obtain information about the DG, you may see the following information messages:

PROP

The next time that plug is set dirty, Maya will propagate the dirty status to the plugs depending on it. For inputs, this includes the affected outputs on the same node as well as all outgoing connections.

BLOCK

The dirty state is not propagated. This is an optimization and means that a dirty state has already been propagated to all dependent plugs so it does not have to be repeated again.

DIRTY

Connection coming into or going out of the plug is dirty and needs an evaluation in order to yield the correct value.

CLEAN

The opposite of dirty, and the values and connections are fully evaluated and correct.