in_avail - Return the number of available in an input stream's
buffer.
istreamhandle in_avail -> istreamhandle available_characters
This function provides a direct interface to
the C++ istream::rdbuf()->in_avail() member function.
R Kupper
May 05 1999
/var/www/debian/nest/nest-simulator-2.20.0/sli/sli_io.cc