1C. identifiers and types
identifiers are strings that the programmer uses to denote certain
objects, in most cases variables, or even keywords or function names
predefined by the compiler. An identifier may consist of:

- upper and lowercase characters
- "0" .. "9" (except as first character)
- "_" (the underscore)

All characters are significant, but the compiler just looks at the
first two to identify the type of identifier it is dealing with:

both uppercase:               - keyword like IF, PROC etc.
                              - constant, like MAX_LENGTH
                              - assembly mnemonic, like MOVE
first lowercase:              - identifier of variable/label/object etc.
first upper and second lower: - E system function like: WriteF()
                              - library call: OpenWindow()

Note that all identifiers obey this syntax, for example:
WBenchToFront() becomes WbenchToFront()