A multi-line chart displays budget projections for Block IV SSN over time, with each line representing a distinct SSN and its delivery estimates. The chart uses D3's `scaleTime` for both axes, `line` with `curveBasis` for smoothing, and `nest` to group data by SSN, colored via `schemeCategory10`. A custom `colorLegend` function renders the legend. The data, sourced from a CSV file, is parsed into `Date` objects for the x and y axes, showing delivery dates against budget years.