Mass currents and singularities in 3He-A

It is shown that the particular form of the mass current 3He-A found by Cross is equivalent to a phenomenological assumption that the current depends only on the traceless part of the tensor Ωsub(ij) introduced by Mermin and Ho to describe spatial variations of the order parameter. An equation of motion for Ωsub(ij) is derived in terms of the vector C introduced previously by the author to describe temporal variations of the order parameter. The appropriate generalizations of curl vsub(s) 0 and the quantization of circulation for 3He-A are derived in terms of Ωsub(ij), and the nature of possible singularities is discussed. (author)