This consolidated version of IEC 60061-1 is based on the third edition (1969) and its supplements A(1970), B(1971), C(1972), D(1972), E(1972), F(1975), G(1977), H(1977), J(1980), K(1983), L(1987), M(1989), N(1992), P(1994), Q(1994), R(1995), S(1996), T(1996), U(1996), V(1997), and amendments 21(1998), 22(1999), 23(1999), 24(2000), 25(2001), 2