A conserved Parity Operator
  The symmetry of Nature under a Space Inversion is described by a Parity operator. Contrary to popular belief, the Parity operator is not unique. The choice of the Parity operator requires several arbitrary decisions to be made. It is shown that alternative, equally plausible, choices leads to the definition of a Parity operator that is conserved by the Weak Interactions. The operator commonly known as CP is a more appropriate choice for a Parity operator. 
Mark J Hadley