The Model-by-model secondary structures show the Kabsch & Sander (1983) secondary structure assignments for each of the models in the NMR ensemble.
These can be useful for seeing which models possess the expected secondary structures, and which may be losing the requisite hydrogen-bonding patterns.
The main options for the Model-by-model secondary structures are:-
These options can be altered by editing the parameter file, procheck_nmr.prm, as described here.