IHW_PPOL
--------

 o Note in data set description that none of these observations have been 
   corrected for polarization bias.

 o The position angle given is with respect to the scattering plane.  Note
   this in the label column definitions.  90 degrees = positive polarization.
   0 degrees = in the plane of polarization.  (Definition is on p. 223 of
   Summary volume - definition of "Angle" in Table XVII.)

 o Column 5 bandpasses are occasionally I4 instead of I3 - check this.