Another take on this is that a single-degree-of-freedom mechanism can have its movement described by one number. That number might refer to translation or rotation, and the number could be positive or negative, but it must be a single number.
The mechanism can consist of more than one moving part. See the picture of the four bar linkage at
http://www.learnengineering.org/2013...mechanics.html , for example.
If there is a more complicated part that your team wishes to use, I suggest posting in the official forum. You don't want a hardware inspector to rule that a part is illegal when you get to an event.