  Experimental data on the pp -> pn pi^+ reaction measured in an exclusive
two-arm experiment at 800 MeV show a narrow peak arising from the strong
proton-neutron final-state interaction. It was claimed, within the framework of
a certain model, that this peak contained up to a 25% spin-singlet final state
contribution. By comparing the data with those of pp -> d pi^+ in a largely
model-independent way, it is here demonstrated that at all the angles measured
the whole of the peak could be explained as being due to spin-triplet final
states, with the spin-singlet being at most a few percent. Good qualitative
agreement with the measured proton analysing power is also found within this
approach.
