guinness and water, This is my understanding from using AutoIt - I do not have access to the core code (nor would I understand it if I did! ): If not otherwise specified in the code, variables are scoped accoding to their location: Global if in main script; Local if in a function. In the Global case the variable is accessible throughout the script; If Local it is available in that function only and can only be referenced elsewhere if passed as a parameter. If specified in the code as Global