Search for “ERTTI” and “G__isinterpretedp2f” in the http://root.cern.ch/svn/cint/trunk/doc/ref.txt reference manual for cint/makecint and good luck!
(See also the very last paragraph in the http://root.cern.ch/drupal/content/how-call-cernlib-routines-interpreter but only if you survive my first above advice.)