The conformance statement clearly states that there SHALL be exactly one performer, however the narrative text seems to contradict that statement in several places.

This performer represents a clinicians who actually and principally carry out the serviceEvent. Typically, these are clinicians who have surgical privileges in their institutions such as Surgeons, Obstetrician/Gynecologists, and Family Practice Physicians. ... There may be more than one primary performer in the case of complicated surgeries. There are occasionally co-surgeons. ... Typically two Operative Notes are generated; however, each will list the other as a co-surgeon.

Notice the plurals in the first sentences (including a grammatical error), and the ambiguous wording in the rest of the narrative guidance. If there are co-surgeons, how specifically should that be modeled? Should we allow multiple cardinality for the performer (PPRF) in that case? An example for that specific case would be helpful.