This standard presents symbols and definitions that may be used in constructing schematic diagrams for mechanical and acoustical systems whose performances are describable by finite sets of scalar variables. The choice of symbols described herein is based upon the following assumptions: a. A system can be divided conceptually into a finite set of elements each of whose dynamical properties are known. b. To each such conceptual element there can be assigned a set of terminals. c. Symbols for the elements shall be interconnected to form a schematic diagram for the whole system so that field equations shall be satisfied at every junction point and around every closed loop. The symbols which appear in this standard were evolved with the following principles in mind: a. It shall be possible to draw the symbols easily and quickly. b. The symbol shall be distinctive and where feasible shall suggest some well-known embodiment of the element in question. c. The symbols shall preferably have been used previously in the scientific literature. NOTE 1. Questions concerning the specific form for a so-called equivalent circuit of an electro-mechanical or any other type of mixed system are not within the scope of this standard. NOTE 2. An Appendix (not a part of this standard) provides background information on the use of the symbols in constructing schematic diagrams.