Use one of these forms to insert a new FITS header card into the image header, or to change the value of an existing FITS header card. If you specify the optional PROF keyword rather than a buffer number, the new header card will be inserted into the internal PROFILE header (see PROFILE and SAVE PROF). The FITS keyword name may be no longer than 8 characters.
Except for two special cases, a FITS card already in the header with the same name will be replaced. The two exceptions are CHAR=COMMENT and CHAR=HISTORY, which will always add a new COMMENT or HISTORY card, respectively, to the header.
The float_value for the FLOAT keyword should be a floating point constant or an arithmetic expression. The integer_value for the INT keyword should be an integer constant or an arithmetic expression whose result will be rounded to the nearest integer.