Control coupling is a moderate type of coupling. Two modules exhibit control coupling when one module controls the internal logic of the other by passing it information. An example of this is when a module passes a control flag to another module, which uses it to control its flow.
This type of coupling may be acceptable, but an effort should be made to make it known that the coupling exists so that the modules can be tested together. It is beneficial to detect any problems with either of the modules earlier rather than later.