An additional rule holds for combinations of j 1, j 2, and j 3 that are related by a Clebsch-Gordan coefficient or Wigner 3-j symbol: ( − − 1 ) 2 ( j 1 + j 2 + j 3 ) = 1 This identity also holds if the sign of any j i is reversed, or if any of them are substituted with an m i instead.