As best I can tell, the text found here in tanach.tar.Z is derived
from _Biblia Hebraica Stuttgartensia_ (BHS) which in turn is based
on the Leningrad manuscript (Codex Petropolitanus Babylonicus), which
dates from the year 916.  This manuscript has the distinction of being
the oldest dated manuscript containing the entire Bible, but contains
many differences from the accepted, masoretic text.