A manufacturer's Catalogued Peripheral equipped with pushbuttons, lamps, keyboards, displays, or equivalent, etc., for troubleshooting or the PES and/or the controlled application. TE is said to be Pluggage when it may be plugged or unplugged at any time into its associated interface, without any risk to the operators and the application. In all other cases TEs are said to be Fixed. TEs may be Permanently Installed or not. TEs are intended for use by authorized personnel only.