ISO 3511-1:1977

Forms one part of four which provide a universal means of communication between the various interests involved in the design, manufacture, installation and operation of measurement and control equipment used in the process industries. This part establishes a symbols system for use in depicting the basic functions. The system has been limited to the identification of instrument functions and does not provide means of illustrating specific instruments. The definitions are used solely for the purpose of application and understanding of the symbol system.