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   PR #    55
   Absorption line at about 0.53 keV was obtained with Einstein SSS and
   MPC as reported by Madejeski et al. (1991) and was suggested to be a
   red-shifted resonance line of ionized oxygen O VIII in cosmic jet
   boosted to us. Therefore we have to pay much attention to the feature
   of soft x-ray spectrum.We are also interested in the spectral
   variability. Tashiro and Otani et al. found it has a `soft lag'
   property in spectral variations from the Ginga results, as seen in
   some other BL Lac objects (1993). With similarresults obtained from
   PKS2155-304, another BL Lac object, Sembay et al. (1993) pointed out
   that the `soft lag' property supports synchrotron emission model.
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