  We present the final data from the spectroscopic survey of the ROSAT-ESO
Flux-Limited X-ray (REFLEX) catalog of galaxy clusters. The REFLEX survey
covers 4.24 steradians (34% of the entire sky) below a declination of 2.5 deg
and at high Galactic latitude (|b| > 20 deg). The REFLEX catalog includes 447
entries with a median redshift of 0.08 and is better than 90% complete to a
limiting flux fx = 3x10^{-12} erg s^{-1} cm^{-2} (0.1 to 2.4 keV), representing
the largest statistically homogeneous sample of clusters drawn from the ROSAT
All-Sky Survey (RASS) to date. Here we describe the details of the
spectroscopic observations carried out at the ESO 1.5 m, 2.2 m, and 3.6 m
telescopes, as well as the data reduction and redshift measurement techniques.
The spectra typically cover the wavelength range 3600-7500 A at a FWHM
resolution of ~14 A, and the measured redshifts have a total rms error of ~100
km s^{-1}. In total we present 1406 new galaxy redshifts in 192 clusters, most
of which previously did not have any redshift measured. Finally, the
luminosity/redshift distributions of the cluster sample and a comparison to the
no-evolution expectations from the cluster X-ray luminosity function are
presented.
