// Stuff you can do:

integer gMyInteger = 3; // Valid declaration of a global variable.
integer gAnotherInteger = CHANGED_INVENTORY; // Valid declaration of a global variable.
integer gCopiedInteger = gAnotherInteger; // Valid declaration of a global variable.

integer CHAT_CHANNEL = 0; // Valid declaration of a pseudo-constant.

// Stuff you **can't** do:

string gAnotherIntegerAsString = (string)gAnotherInteger;
// ^^^^ ILLEGAL! Global variable declarations are not evaluated. (You can't typecast here.)

float gMyFloat = llFabs(482.334);
// ^^^^ ILLEGAL! Global variable declarations are not evaluated. (You can't call a function here.)

string gMyString = "Hello!" + "Goodbye!";
// ^^^^ ILLEGAL! Global variable declarations are not evaluated. (You can't use operators here.)

// Global functions:

myFunction() {
    gMyInteger = 45; // Valid.
}

integer anotherFunction () {
    return gMyInteger; // Valid.
}

default {
    state_entry() {
        gMyFloat = llFabs(482.334); // Valid.
        gMyInteger = 12; // Valid.
    }
}

state foo {
    touch_start(integer n) {
        llSay(CHAT_CHANNEL, "Touched.");
        gMyInteger = n; // Valid.

        CHAT_CHANNEL = 4; 
        // ^^^^ BAD CODING PRACTICE! Changing the value of a pseudo-constant is legal, since LSL doesnt 
        // have user-defined constants, but you will go to hell for this - after some very nasty debugging
    }
}