When one selects a board within Arduino IDE, a preprocessor definition is added to one of the behind-the-scenes files.
After a lot of hunting and some good fortune I found that the format of this definition is:
Some are easy to guess (
ARDUINO_AVR_UNO, for example), but others are less so. The Pro Micro has '16' or '8' appended to the definition depending on the speed. I do not know if the definition is different for 5V or 3.3V. I haven't managed to guess the definition for the Mega2560, but it isn't anything obvious.
Question 1: Is there a list in existence of the possible definitions?
Question 2: Is there any distinction, as far as compilation and preprocessor involvement is concerned, between BoardX-5V and BoardX-3.3V, and how is this distinction defined?