On Thu, 16 Dec 2010, Al Kossow wrote:
  There was an attempt at establishing what can
roughly be described as an upside down Q
 for a slashed O. The only example I know of where someone used this are in line printer
listings
 from SDS in the late 60's. I would have to do some serious digging in magazines to
find who was
 pushing this as a standard. They end up looking like misformed  8's.
 It does terrible things to OCR. 
 Microsoft's first attempt at OCR customer order forms used it!
 Haven't seen it since.
 In the 1960s, I remember a few old farts who slashed O's (to differentiate
 them from zeroes!)  One of the teachers that I had in 1967 used to do it.
 He never liked me, because I asked a lot of weird questions.
 He was one of my favorite teachers, because he could answer those weird
 questions!
 I assume that they are all dead now.  When I began teaching in 1983, he
 had recently passed, and they gave me his old desk!
 
 The old swedish standard for distinguishing zero (0) was with a slash (?
 which is a big ?.)
 That convention clashes with the norwegian ?.
 ? (swedish) = ? (norwegian)