  Multiwavelength followup of unidentified Fermi sources has vastly expanded
the number of known galactic-field "black widow" and "redback" millisecond
pulsar binaries. Focusing on their rotation-powered state, we interpret the
radio to X-ray phenomenology in a consistent framework. We advocate the
existence of two distinct modes differing in their intrabinary shock
orientation, distinguished by the phase-centering of the double-peaked X-ray
orbital modulation originating from mildly-relativistic Doppler boosting. By
constructing a geometric model for radio eclipses, we constrain the shock
geometry as functions of binary inclination and shock stand-off $R_0$. We
develop synthetic X-ray synchrotron orbital light curves and explore the model
parameter space allowed by radio eclipse constraints applied on archetypal
systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the
stand-off is $R_0 \sim 0.15$ -- $0.3$ fraction of binary separation from the
companion center, depending on the orbit inclination. Constructed X-ray light
curves for B1957+20 using these values are qualitatively consistent with those
observed, and we find occultation of the shock by the companion as a minor
influence, demanding significant Doppler factors to yield double peaks. For
J1023+0038, radio eclipses imply $R_0 \lesssim 0.4$ while X-ray light curves
suggest $0.1\lesssim R_0 \lesssim 0.3$ (from the pulsar). Degeneracies in the
model parameter space encourage further development to include transport
considerations. Generically, the spatial variation along the shock of the
underlying electron power-law index should yield energy-dependence in the shape
of light curves motivating future X-ray phase-resolved spectroscopic studies to
probe the unknown physics of pulsar winds and relativistic shock acceleration
therein.
