Cis/trans isomers at double bonds may be specified in terms of the order of the substituents; the Natta notation, which uses wedges to indicate the spatial orientation in or out of the paper plane, is commonly used to describe tetrahedral chiral centers. Considering the neighborhood of a vertex as a circularly ordered instead of a plain set is sufficient to capture localized chirality . It would thus be possible to handle chirality in the context of cut-and-join operations by inserting join edges into circularly ordered lists at the same places where the severed edges have been. Similarly, one could also deliberately invert chirality during the crossover operation. Moreover, the orientation of a chiral center is also a very natural mutation operation on molecular graphs with chirality annotation.