4.3 Labels
Labels are the targets of Goto instructions and the various branching instructions (such as IfErrors, MessageBox, IfFileExists, and StrCmp). Labels must be within a Section or a Function. Labels are local in scope, meaning they are only accessible from within the Section or Function that they reside in. To declare a label, simply use:
MyLabel:
Labels cannot begin with a -, +, !, $, or 0-9. When specifying labels for the various instructions that require them, remember that both an empty string ("") and 0 both represent the next instruction (meaning no Goto will occur). Labels beginning with a period (.) are global, meaning you can jump to them from any function or section (though you cannot jump to an uninstall global label from the installer, and vice versa).