Command names, function names, labels, variable names, file names, etc are not case sensitive, so that “Run” and “RUN” are equivalent and “dOO” and “Doo” refer to the same variable.
There are two types of variable: numeric which stores a floating point number (eg, 45.386), and string which stores a string of characters (eg, “Tom”). String variable names are terminated with a $ symbol (eg, name$) while numeric variables are not.
Variable names and labels can start with an alphabetic character or underscore and can contain any alphabetic or numeric character, the period (.) and the underscore (_). They may be up to 32 characters long. A variable name or a label must not be the same as a function or one of the following keywords: THEN, ELSE, GOTO, GOSUB, TO, STEP, FOR, WHILE, UNTIL, LOAD, MOD, NOT, AND, OR, XOR. Eg, step = 5 is illegal as STEP is a keyword. In addition, a label cannot be the same as a command name.