continuum. Within the modulated pairing scenario, which reproduces the correlation of the coherence peaks’ weight and position with the dopant atoms imaged by STS,[@mcelroyscience] the presence or absence of Ni resonances is therefore dependent on whether or not interstitial out-of-plane oxygen dopants exist nearby.

![(Color online) Schematic picture of a small-gap region. Circles are ionic sites, X represents an impurity, and the bonds represent the absolute values of the bond order parameter $\Delta$ on bonds in the bulk (top) and in a small gap patch (bottom). []{data-label="schematic"}](schematic.eps){width="1.0\columnwidth"}

We further consider the effect of gap modulation on the Zn resonance near the Fermi level. Here it appears unlikely that the suppression and broadening of the coherence peaks in large-gap regions can alone suppress the impurity resonance because of its weak coupling to the continuum. There is very little experimental data on the variation of the spectral form, weight, and position of the resonance in correlation with the local gap size, but it appears from what is available[@davis; @hoffmanthesis] that there is considerable dispersion of all these quantities which makes it difficult to extract systematics. Some of this dispersion may simply be due to the well-known very strong interference of near-unitary impurity 