Coverage Criteria, What are independent conditions exactly?

When speaking of coverage criteria such as MCDC (Modified Condition/Decision Criteria)...

It is stated that "Every point of entry and exit in the program has been invoked at least once, every condition in a decision in the program has taken all possible outcomes at least once, and each condition has been shown to affect that decision outcome independently. A condition is shown to affect a decision's outcome independently by varying just that condition while holding fixed all other possible conditions. [...]" - http://ift.tt/1SIdFrn

This description is rather vague of what constitutes an independent criteria... So, what are they? Examples are helpful in any language (C-family/python/haskell preferred).