What constitutes a side trip on an itinerary? I have a fare that says, "End on End not permitted. Side trips permitted."

Suppose I have a roundtrip fare JFK-NCE with a layover in CDG; can I add a roundtrip CDG-MUC in the middle of this? Thus, the outbound itinerary is JFK-CDG-MUC-CDG-NCE, and the inbound trip is NCE-CDG-JFK.

Is this correct? Am I missing anything?