Mandatory Calibration File Keywords defined by the HEASARC Calibration data to be incorporated into the HEASARC calibration database are FITS formatted files (generally images or binary tables or some combination). The following keywords need to be added to the headers of all extensions of calibration datasets meant to be part of the HEASARC Calibration Database. These keywords represent the minimum amount of information necessary in order to create a calibration index file for the given dataset. Calibration File Keyword Description Index File Column Name TELESCOP The name of the satellite or mission. Allowed Values are given in OGIP/93-013 TELESCOPE INSTRUME Name of the instrument. Allowed values given in OGIP/93-013 INSTRUME DETNAM Name of the detector. Only applicable if INSTRUME value is ambiguous. Values given in OGIP/93-013 DETNAM FILTER Name of the filter in use, if applicable FILTER CCLSmmmm HEASARC class of the calibration file (PCF, BCF, CPF, USR) CAL_CLAS CDTPmmmm Distinguishes "real" (DATA) or "virtual" (TASK) calibration information CAL_DTYP CCNMmmmm Contents Descriptor. See the CAL_CNAM Dictionary or Appendix A of CAL/GEN/92-011 for defined values. CAL_CNAM CBDnmmmm Parameter limits for a given calibration dataset. Syntax is defined in Section B.3 of CAL/GEN/92-011 CAL_CBD CVSDmmmm Date (UTC) after which calibration dataset can be used CAL_VSD CVSTmmmm Time (UTC) of day on specified CVSDmmmm after which calibration dataset can be used CAL_VST CDESmmmm Descriptive summary of calibration dataset CAL_DESC