The resulting data show the following trends: First, there is a trend to increasing adsorption energies with increasing number of Ag neighbors (decreasing Pt ensemble size) in the low coverage limit (1 COad per ensemble), even though the increase is rather small. Second, also the differences between different adsorption sites are small, very much in contrast to earlier finding of distinct ensemble effects for CO adsorption on Pdn ensembles in PdAg/Pd(111) and PdAu/Pd(111) surface alloys, where the most favorable adsorption site changes from on-top for Pd1 monomers to adsorption on Pd2 bridge sites for Pd2 dimers and finally Pd3 threefold hollow sites on compact Pd3 trimers. In contrast, for PtAg/Pt(111) adsorption on on-top sites is most favorable for Pt1, Pt2 and Pt3 ensembles, although the differences are small for the latter two. While these trends were reported already earlier, we now furthermore find that there is also little .