The properties of a relativistic plasma dispersion function (RPDF) for an i
ntrinsically extremely relativist, strongly magnetized, one-dimensional, el
ectron-position plasma are discussed in detail. For a plasma with a mean Lo
rentz factor [gamma] much greater than 1 in its rest frame, the RPDF has a
large peak > [gamma] at a phase speed a fractrion of order 1/[gamma] below
the speed of light, and the asymptotic value (infinite phase speed) is [gam
ma(-3)] similar to 1/[gamma]. These features are not particularly sensitive
to the choice of distribution function, The RPDF is used to discuss the pr
operties of waves in such plasmas. Particular points discussed are the impl
ications of the RPDF for the maximum frequency for parallel Langmuir waves:
and for the reconnection between the Langmuir mode and the Alfven mode.