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   62142
   The different spectral properties of blazar subclasses provide
   important clues about the nature of these objects. The steep X-ray
   spectra of High-energy peaked BL Lacs, together with their flat values
   of the radio-to-X-ray indices, alpha-rx, indicate that these objects
   are synchrotron-dominated, while inverse Compton emission plays a more
   important role in Low-energy peaked BL Lacs and FSRQs as indicated by
   their flat X-ray continua and steep alpha-rx indices. We have found a
   new FSRQ subclass with unexpectedly steep ROSAT spectra (photon index >
   2) and alpha-rx intermediate between HBLs and LBLs. We propose to
   observe with ASCA the 7 brightest steep X-ray FSRQs to determine the
   shape of their high-energy continua for the first time and clarify
   their role in the blazar family.
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