lines is synthesized with an iron abundance of zero to ensure the feature of interest vanishes and that no other elements or molecules contribute to the spectral line. The resulting sample of iron lines is typically reduced to $\sim$12. The uncertainty for each measured iron line is determined by examining the residual between the synthetic and actual spectrum and finding the abundance which causes the residual to differ visually from the noise. The weighted average is computed for all of the individually examined iron lines and then set as the iron abundance for the synthesis of the rest of the elements. The error of the weighted mean is taken to be the final abundance uncertainty; this method is used to compute the uncertainties in all infrared abundance calculations except in the case of oxygen.

Oxygen has a slight dependance on the carbon abundance through CO formation an initial carbon abundance is determined from the analysis of a single atomic [C$\;$[Roman[1]{}]{}]{} line and several CO features, where carbon is much more sensitive than oxygen. With carbon fixed, the oxygen is then determined by synthesizing OH lines (see Fig. \[fig:OHline\]).ÊThe new oxygen abundance is fixed, and the carbon redetermined. This iteration is 