|EPOCH||D||Julian Epoch for mean coordinates|
|DATE||D||Modified Julian Date (JD-2400000.5) for true coordinates|
|RMATPN||D(3,3)||combined precession/nutation matrix|
vtrue = Mvmeanwhere vtrue is the star vector relative to the true equator and equinox of epoch DATE, M is the matrix RMATPN and vmean is the star vector relative to the mean equator and equinox of epoch EPOCH.
SLALIB --- Positional Astronomy Library