Pressure measurement because atmospheric pressure is always changing and the reference in this case is fixed at 1 bar. To produce an absolute pressure sensor, the manufacturer seals a high vacuum behind the sensing diaphragm. If the process-pressure connection of an absolute-pressure transmitter is open to the air, it will read the actual barometric pressure. The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N·m or kg·m·s). This special name for the unit was added in 1971; before that, pressure in SI was expressed in units such as N·m. When indicated, the zero reference is
Free Pascal or improved. The project has a "compilation mode" concept and the developers made it clear that they would incorporate working patches for the standardized dialects of the American National Standards Institute (ANSI) and International Organization for Standardization (ISO), to create a standards-compliant mode. A small effort has been made to support some of the Apple Pascal syntax to ease interfacing to the Classic Mac OS and macOS. Since the Apple dialect implements some standard Pascal features that Turbo Pascal and Delphi omit, Free Pascal is a bit more ISO-compatible than these. The 2.2."x" release series did not significantly change the