  The GLAST LAT calibration infrastructure is designed to accommodate a wide
range of time-varying data types, including at a minimum hardware status bits,
conversion constants, and alignment for the GLAST LAT instrument and its
prototypes. The system will support persistent XML and ROOT data to begin with;
other physical formats will be added if necessary. In addition to the "bulk
data", each data set will have associated with it a row in a rdbms table
containing metadata, such as timestamps, data format, pointer to the location
of the bulk data, etc., which will be used to identify and locate the
appropriate data set for a particular application.
  As GLAST uses the Gaudi framework for event processing, the Calibration
Infrastructure makes use of several Gaudi elements and concepts, such as
conversion services, converters and data objects and implements the prescribed
Gaudi interfaces (IDetDataSvc, IValidity, ..). This insures that calibration
data will always be valid and appropriate for the event being processed. The
persistent representation of a calibration dataset as two physical pieces in
different formats complicates the conversion process somewhat: two cooperating
conversion services are involved in the conversion of any single dataset.
