[*HST*]{} to address these and other fundamental aspects of the stellar population. The major focus is on the metallicity and its distribution. That is because giant-branch loci are much more sensitive to Z than age, so conclusions about Z are relatively independent of the assumed age. The breadth of the giant branch implies a [*wide*]{} range in Z, from roughly solar down to below $-1.0$ dex. Paradoxically though, the distribution is rather narrow when judged by its FWHM compared to either the closed-box model of chemical enrichment or the distribution of metallicity in the solar neighborhood. Evidence for a wide giant branch and broad total range in Z was available before from pioneering ground-based CM diagrams in [*V*]{} and [*I*]{} by Freedman (1989) and Davidge & Jones (1992). However, it is clear now that the old data were just the tip of the iceberg — the present data give a [*much*]{} fuller picture of the upper giant branch, and a correspondingly greater total width in .

A second focus is comparison with mean population age and Z deduced from ground-based integrated spectral indices. We can infer these values using Worthey models for the [*HST*]{} field by slight outward extrapolation of 