Dumb question: What IS a trigraph?

[Doug Gwyn]

In article <479.nlhp3 at oracle.nl> bengsig at oracle.nl (Bjorn Engsig) writes:
>Article <10762 at smoke.BRL.MIL> by gwyn at brl.arpa (Doug Gwyn) says:
>|Unless you're importing a lot of code from
>|European sites or are implementing a C compiler, you shouldn't have to
>|be concerned about trigraphs, ...
>Well, I don't think that any Europeans use trigraphs.

I didn't say they did.  In the future, once there is a sufficient
desity of standard-conforming C implementations, it is possible that
C source files being transported between sites that operate in
radically different environments will often be mapped to/from trigraphs
to avoid national character-set problems during the port.