USGS DEM format

From: Greg Travis
      Agriculture and Agri-food Canada
      Research Station
      Box 3000
      Lethbridge, Alberta
      T1J 4B1

I have purchased DEM data from our provincial dept of surveys
and mapping. The format is not the same as that used in USGS
DEM's and consequently, I cannot use m.dem.extract. If possible,
I would appreciate a terse description of the format the USGS
provides their DEM's in and I can re-format my provincial DEM's
accordingly.

thank you.