Hi,
It is allowed to use the “RotateMotorPID” function of NXC?
Best, Ana
Hi Ana,
sure, you can use it! You can use every standard API function of any software/robotics platform. Why do you think it might not be allowed? According to 2.2.1 you are only not permitted to use robotics kits that are explicitly sold as kits to be used for RoboCup.
Just make sure you know what you are doing and that you can explain it during the competition to the interviewers, especially how and why you selected the P, I and D parameters. 
Best,
Jan