  It is known that the orbital angular momentum of a paraxial beam is related
to the rotational motion of the instantaneous field pattern representing the
electric field optical-frequency oscillations [arXiv:0812.0888; J. Opt. A: Pure
Appl. Opt 11, 094004, (2009)]. Now this conclusion is generalized: any
identifiable directed motion of the instantaneous 2D pattern of the field
oscillation ("running" behaviour of the instant oscillation pattern)
corresponds to the transverse energy flow in the experimentally observable
time-averaged field. The transverse orbital flow density can be treated as a
natural geometric and kinematic characteristic of this running behaviour.
