The tables with register addreses, names and bit layout are generated from GCC .h (C) header files or BASCOM .DAT (B) files. The content of the tables is created automatically and therefore this resource is not 100% waterproof. Moving cursor over the table gives us the bit layout of the underlaying register.
There is a comfortable way to change the generated data and their properties (e.g.color). In case of failure or improvements please drop me a mail (contact is on the home page).
The illustration picture on the right has nothing to do with AVR or Arduino concept. It is a printed circuit board from an old, maybe digital equipment.