The gas control assembly includes a control body threaded to a vessel neck to extend into the vessel containing pressurized fluid and has a fitting in the body bore which in conjunction therewith provides a part of a first fluid passageway from an inlet in the vessel and an outlet to the ambient atmosphere. A gap is formed between the first and second optical sections. The system parameter message including the associated stream length information is transmitted separately from the data stream. The guide edge serves to prevent the steel ball from being inseparably arrested by the washer. The refractive index of the body is ni and i is a positive integer. The lift member has a blunt end fork with a pair of tongs forming a channel therebetween opening at a lift member distal end away from the shank.