DEFINE HEADER

        [SIC\]DEFINE  HEADER Var1 File1 Key1 [Var2 File2 Key2 [...]] [/GLOB-
    AL]

    Define variables associated to the HEADER of the GILDAS  images  located
    in  the  specified  files. The Keyword must be either READ or WRITE. The
    following variables are defined:

       VAR%GENE       Integer        Length of general section
       VAR%NDIM       Integer        Number of dimensions (ReadOnly)
       VAR%DIM        Integer[4]     Dimensions           (ReadOnly)
       VAR%CONVERT    Double[3,4]    Conversion formulae for the 4 axes:
                                     Reference pixel,
                                     Value at reference pixel,
                                     Increment
       VAR%BLAN       Integer        Length of blanking section
       VAR%BLANK      Real[2]        Blanking and tolerance
       VAR%EXTREMA    Integer        Length of extrema section
       VAR%MAX        Real           Maximum
       VAR%MIN        Real           Minimum
       VAR%WHERE      Integer[4,2]   Position of max and min
       VAR%DESC       Integer        Length of units and coordinate system secti
       VAR%UNIT       Char*12        Image unit
       VAR%UNIT1      Char*12        First axis type
       VAR%UNIT2      Char*12        Second axis type
       VAR%UNIT3      Char*12        Third axis type
       VAR%UNIT4      Char*12        Fourth axis type
       VAR%SYSTEM     Char*12        Coordinate system
       VAR%POSI       Integer        Length of position section
       VAR%SOURCE     Char*12        Source name
       VAR%RA         Double         Right Ascension
       VAR%DEC        Double         Declination
       VAR%LII        Double         Galactic longitude
       VAR%BII        Double         Galactic latitude
       VAR%EPOCH      Real           Epoch of coordinates
       VAR%PROJ       Integer        Length of projection section
       VAR%PTYPE      Integer        Projection type (code)
       VAR%A0         Double         First coordinate of projection center
       VAR%D0         Double         Second coordinate of projection center
       VAR%ANGLE      Double         Position angle of projection
       VAR%X_AXIS     Integer        First projected axis
       VAR%Y_AXIS     Integer        Second projected axis
       VAR%SPEC       Integer        Length of spectroscopy section
       VAR%LINE       Char*12        Line name
       VAR%FREQRES    Double         Frequency resolution
       VAR%FREQOFF    Double         Frequency offset
       VAR%RESTFRE    Double         Rest Frequency
       VAR%VELRES     Real           Velocity resolution
       VAR%VELOFF     Real           Velocity offset
       VAR%F_AXIS     Integer        Frequency/Velocity axis
       VAR%BEAM       Integer        Length of beam section
       VAR%MAJOR      Real           Major axis of beam
       VAR%MINOR      Real           Minor axis of beam
       VAR%PA         Real           Position angle of beam

    where VAR is the specified variable name for the header. VAR  becomes  a
    dummy variable of type header, which can only be referenced in a further
    DELETE /VARIABLE command. The VAR%item variables are ReadOnly  or  Read-
    Write  according to the keyword Key, except for the dimension variables,
    which cannot be modified.