A method is provided for manufacturing a silica glass that is substantially free of chlorine. The apparatus includes a number of distributed clients run on registered computers, gathering policy advisories and reporting relevance to a system administrator. The gas-measuring device has an infrared radiation source, a pyramid-like beam splitter, and a quadrant detector, which has two measuring detectors and two reference detectors. Illustratively, any command code, that is only one bit different from a legal command, will be an illegal command.