I'm a stickler for following best practices. So I use the Validation feature of Cameo 18.5 to ensure the correctness of my models. However, I've noticed a number of what I believe to be false positive validation errors generated by the tool.
Under the UML completeness constraints, messages, data objects, and other "data" objects are being considered as activities, causing the ActOutEdg and ActInEdg validation to fail.
Under Spelling, documentation and TO_DO tags cause spelling errors, even when there is nothing inside of them!