Nicholas Bodley wrote:

>Apparently, most Americans (maybe including Canadians) are extremely
>confused about which is a backslash and which is a forward slash. There
>must be some significant number of instances of the likes of "2\3" for
>"2/3"; iirc, the backslosh actually did have a special meaning in such a
>context; it was a variant of division, possibly modular arithmetic.
>(Modular arith.: Daytime given, if it's now 11:00, what time will it be
>exactly four hours from now? The modulus is 12, in this case.) Btw, the
>BBC always uses the expression "forward slash" when speaking URLs.
>
>

Backslash is used by some mathematicians for set difference (i.e. A \ B
is the set of things in set A which are not in set B, or A∪B′). Others
use the normal minus sign. (cf. Unicode U+2216 SET MINUS)

I heard on another list (or maybe this one) that "forward slash" is used
in the BBC because "slash" is slang for "urinate," which doesn't really
answer why nobody gets upset by the letter p also... Besides, people
who'd been working on computers already had backslashes pounded into
their brains because they're what DOS/Windows use for directories, and
so need to be "reminded" that even though they're typing on a computer,
and even though the slashes seem to act as directory delimiters, they're
still *forward* slashes (as in UNIX), not backslashes. Still, I've seen
URLs (sometimes even in HTML links, which makes things fail) use
backslashes instead.

~mark