The iostream classes implement most of the features of AT&T
version 2.0 iostream library classes, and most of the features
of the ANSI X3J16 library draft (which is based on the AT&T design).
These classes are available in libg++ for convenience and for
compatibility with older releases; however, since the iostream classes
are licensed under less stringent terms than libg++, they are now
also available in a separate library called libio---and
documented in a separate manual, corresponding to that library.
See section `Introduction' in The GNU C++ Iostream Library.