[Maxima] question about taylor

[S. Newhouse]

Hello,
 Could someone please explain the "g2304" in the following output?

TIA,
 -sen

(%i23) t1: taylor(sin(x+y),[x,y],[0,0],[2,2]);
(%o23)/T/                        y + x + . . .
(%i24) r1: taytorat(%);
(%o24)/R/                        (x + y) g2304