#FITS    CDF                Comment
#----    ---                -------
EXTNAME  HDU_Extension_Name // HDU extension name
DATE     File_Creation_Date // File createion date
DATE-OBS Observation_Date   // Observation date
DATE_OBS Observation_Date_Time  // Observation date & time (SOHO/FITS convetion)
TIME-OBS Observation_Time   // Observation time
OBSERVER PI_name            // person/entity that acquired the data
ORIGIN   PI_affiliation     // Institution/org who created the FITS file
AUTHOR   Author             // Person who compiled the metadata
TELESCOP Satellite          // Satellite or telescope
INSTRUME Instrument         // Instrument
OBJECT   Object_Observed    // Name of the object observed
REFERENC Reference          // Reference where the data are published
DATAMAX  Max_Value          // Max value in the array (physical)
DATAMIN  Min_Value          // Min value in the array (physical)
EQUINOX  Equinox            // Equinox in years for the celestial coordination
CTYPE1   ctype1             // Name of the coordinate represented by axis 1
CTYPE2   ctype2             // Name of the coordinate represented by axis 2
CTYPE3   ctype3             // Name of the coordinate represented by axis 3
CRPIX1   crpx1              // Location of a reference point along axis 1 
CRPIX2   crpx2              // Location of a reference point along axis 2
CRPIX3   crpx3              // Location of a reference point along axis 3
CRVAL1   crval1             // Value specified by CTYPE1 at CRPIX1 
CRVAL2   crval2             // Value specified by CTYPE2 at CRPIX2
CRVAL3   crval3             // Value specified by CTYPE3 at CRPIX3
CDELT1   cdelt1             // Partial derivative specified by CTYPE1 at CRPIX1
CDELT2   cdelt2             // Partial derivative specified by CTYPE2 at CRPIX2
CDELT3   cdelt3             // Partial derivative specified by CTYPE3 at CRPIX3
CROTA1   crota1             // Rotation from CTYPE1 to a diff coordinate system
CROTA2   crota2             // Rotation from CTYPE2 to a diff coordinate system
CROTA3   crota3             // Rotation from CTYPE3 to a diff coordinate system
CUNIT1   cunit1             // Unit for CTYPE1 - not FITS standard
CUNIT2   cunit2             // Unit for CTYPE2 - not FITS standard
CUNIT3   cunit3             // Unit for CTYPE3 - not FITS standard

# The asterisk (*) is a placeholder indicator and its corresponding mapping
# attribute is created in the output file.  The following example creates
# 2 attributes (P1 and P2), if uncommented.  The value
# of P1 and P2 will be "Placeholder 1" and "Placeholder 2", resctively.

#  *    P1                     // Placeholder 1
#  *    P2                     // Placeholder 2