This is an ASCII file with no specific format. The existence of an MSG at the end of a Model, Tool or UI execution signals a warning to the FUI. All executables may create the MSG file. This provides a mechanism to detect messages, through the existance of the MSG file. Executables are expected to write messages during processing. If the MSG file exists when control is given back to the FUI, it is read and shown to the user through the message window.