STScI . ... Reference Data for Calibration and Tools . ... Delivery Procedures . ... Delivery of Reference Files . ... The end result is the ingest of the reference files into the Calibration Reference Data System (CRDS) or the Exposure Time Calculators (ETC) and the Python Synthetic Photometry Package ( pysynphot ) repositories, the HST's ground system reduction pipeline ( OPUS ), their archiving in the Data Archiving and Distribution System (DADS), and their inclusion in the STScI on-line archives. ...