  We present an accurate characterisation of the high-resolution X-ray spectrum
of the Narrow Line Seyfert 1 galaxy Arakelian 564 and put it in to context with
other objects of its type by making a detailed comparison of their spectra. The
best fit to the data identifies five significant emission lines at 18.9, 22.1,
24.7, 29.0 and 33.5A due O VIII Ly alpha, O VII(f), N VII Ly alpha, N VI(i) and
C VI Ly alpha respectively. These have an RMS velocity of ~1100km/s and a flow
velocity of ~-600km/s, except for the O VII(f) emission line, which has a flow
velocity consistent with zero. Two separate emitting regions are identified.
Three separate phases of photoionized, X-ray absorbing gas are included in the
fit with ionization parameters log xi=-0.86, 0.87, 2.56 and column densities
N_H=0.89, 2.41, 6.03*10^20cm^-2 respectively. All three phases show this to be
an unusually low velocity outflow (-10pm100km/s) for a narrow line Seyfert 1.
We present the hypothesis that the BLR is the source of the NLR and warm
absorber, and examine optical and UV images from the XMM-Newton Optical Monitor
to relate our findings to the characteristics of the host galaxy.
