Allow controls without code
When we are arranging trainings we usually don't have punching units and control codes on every control. But PurplePen forces us to have that and that is a little annoying, specially for the youngsters. It would be a good idea to be able to ommit or hide the control codes in the control description.
John M commented
Allow controls with 2 letters. Allows far more combinations than with two numbers (some of which can't be used as can be read upside down). The recess on the top of a Sportident box is too small to accommodate 3 numbers without using a narrow font.