What you need to do for a rating
When you fly a plane in the Single Engine Piston (SEP) category, and pass your exam on this type, your license will have the class rating SEP. You can now fly any plane within this category.
To fly a plane in the Multi Engine Piston (MEP) category, you need to take some additional training and pass an exam.Then the MEP class rating will be added to your license.
We train for the Class Rating MEP on the DA-42