  There are now five angular momentum relations or sum rules in the literature:
the Jaffe, Manohar relation for a longitudinally polarized nucleon, and the
Bakker, Leader, Trueman result for the case of transverse polarization; the Ji
relation for longitudinal polarization, and the Leader result for transverse
polarization, both involving generalized parton distributions; and a new sum
rule due to Ji, Xiong and Yuan dealing with the transverse component of the
Pauli-Lubanski vector. I discuss these various relations and examine their
precise interpretation in the light of the so-called "angular momentum
controversy". In particular, I show that the claim of Ji, Xiong and Yuan that
their Pauli-Lubanski relation is frame or energy independent is incorrect, and
that they have missed an energy dependent term in their expression.
