Is kernel/GMPrat.* distributeable?

[brlink@…]

kernel/GMPrat.cc and kernel/GMPrat.h both have the following.

// originally written by Gerd Sussner, sussner@mi.uni-erlangen.de
// copied by Stephan Endrass, endrass@mathematik.uni-mainz.de
// 23.7.99

But Gerd Sußner is not listed anywhere as contributor (in no COPYING, not even in doc/COPYING.texi).

It'd be nice if you could verify that this file is actually allowed to be distributed and under GPL and document that somehow.