Giving names to cards was largely straightforward and
positive.
However, an problem of CRC is the distinction between
class and object is blurred, which is bad for beginners.
The approach of Biddle at el used was to increasingly say that
the cards represented objects, not class, despite the team CRC.
Responsibility is at the core of the CRC card technique, and is
a strong and successful concept.
People find it easy to think of occupational or business roles
that remind them how responsibility works.
Collaborator doesn't mean symmetric relation, but the word itself gives some confusion for some people, who thought one class using another result in each class noting the other as a collaborator. Some people prefer the simpler term "helper", and this made the direction of help clear.