  The spectrum of the transient X-ray binary pulsar A0535+26 obtained by OSSE
in February 1994 shows an absorption feature at 110 keV but does not confirm a
feature at around 55 keV, as previously reported by other instruments. If the
110 keV feature is due to cyclotron scattering at the first harmonic, then the
magnetic field required is about $10^{13}$ Gauss, the highest observed in an
X-ray pulsar. Conversely, if this strong feature is a second harmonic and the
line formation process is such that an extremely weak fundamental results at
$\simeq$ 55 keV, the estimate of the field strength is halved. We present
results of detailed cyclotron line transfer models from two source geometries
to explore the theoretical contraints on the line shapes in this source. It is
found that while a fundamental harmonic line at $\sim$ 55 keV may be partially
filled-in by angle redistribution in cylindrical geometries, the required
viewing angles give a second harmonic line shape inconsistent with the
observation. Interpretation of the feature at 110 keV as a first harmonic seen
at small angles to the field yields more consistent line shapes.
