Passive spin filters are combined with pure in-phase correlation spectroscopy (PICSY) to obtain SIS-(p,q)-PICSY expts., where p and q are the nos. of passive spins that are simultaneously or sequentially inverted during the evolution period and that are coupled to both source and target spins, resp. Conventional PICSY and SIS-(0,1)-PICSY spectra of cyclo-(L-proline1-L-proline2-D-proline3) are compared. [on SciFinder (R)]