> QD (Quad Density). 
On Thu, 26 Jan 2012,
Chuck Guzis wrote:
  But it's not--according to my disks, the QD is 48
tpi double-sided
 MFM. 
But Superbrain argued that if MFM is DOUBLE density, then double SIDED MFM
is "QUAD" density!
  There *is* a 96 tpi format, but I believe it belongs
to the
 Superbrain II. 
SD (SUPER density)
Remember "sizes of olives" ("jumbo colossal", etc.)
Since it is already known that there is "non-stantard" use of terms, WE
need to avoid use of "quad", and talk ONLY in terms of 48 V 96 TPI, etc.