Long file name problem(?) with header files

Has anyone else encountered this?
I had a header reference of

    #include <stdstring>

I left the ".h" off because that's what I normally do with such
STL header files. When I compiled, I got an error because
the compiler couldn't open "Stdstrin.h" without the "g". That is,
BCB truncated the file name to eight characters before adding the ".h".

After floundering around a bit, I added the ".h" and it compiled just
fine.
It does, however, seem a bit odd. Perhaps I've missed a part of the
documentation.

Tom