  Detailed study of the energy and momentum carried by the electromagnetic
field can be a source of clues to possible new physics underlying the Maxwell
Equations. But such study has been impeded by expressions for the parameters of
the electromagnetic energy flow that are inconsistent with the transformation
rules of special relativity.
  This paper begins by correcting a basic parameter, the local velocity of
electromagnetic energy flow. This correction is derived by the direct
application of the transformation rules of special relativity.
  After this correction, the electromagnetic energy-momentum tensor can then be
expressed in a reference system comoving with the energy flow. This tensor can
be made diagonal in the comoving system, and brought into a canonical form
depending only on the energy density and one other parameter.
  The corrected energy flow and its energy-momentum tensor are illustrated by a
simple example using static electric and magnetic fields
  The proposal that electromagnetic momentum results from the motion of a
relativistic mass contained in the fields is examined in the context of the
corrected flow velocity. It is found that electromagnetic field momentum,
though real, cannot be explained as due only to the motion of relativistic
mass.
  The paper concludes that introducing the requirement of consistency with
special relativity opens the study of electromagnetic energy and momentum to
new possibilities.
