  A new mechanism for the pp --> pp pi0 reaction close to threshold is
suggested coming from the isoscalar excitation of the Roper and its decay into
N(pi pi)S-wave, with one of the pi0 emitted and the other one reabsorbed on the
second nucleon. The mechanism can lead to important interference with other
mechanisms and, together with experiment, serves to exclude large ranges of the
2pi N* decay parameters allowed by the N* partial decay widths.
