I would really like an explanation of MOD-TYPE casting error, what they are, and why they are produced? I have no idea what it is besides the fact that I got one.

Also an explanation of that "fixed" declaration would be nice, I have never declared a variable of the fixed type. I mainly have always used var, int, bool, and float (along with pointers and strings and of course variants of the mentioned before like: structs, arrays, vectors, etc...).
But I have never used fixed, don't know what they are, how they work, what they are good for, what their limitations are, etc...

At first I thought it might be something similar to "static" due to its name, but after reading the entry in the manual it is obviously not the case. Anyway I really didn't understand what it is good for or how it works by the short definition in the manual, any further explanation would be apreciated.