This routine is obsolete and has been replaced with ENVIRasterMetadata.

Use this procedure to set user-defined header values, which are in addition to the standard ENVI header keywords set using ENVI_SETUP_HEAD or ENVI_ENTER_DATA. User-defined header values use the same KEYWORD=value format as the standard ENVI header values. Use the procedure ENVI_WRITE_FILE_HEADER to write the new ENVI header to disk.

Note: User-defined keywords can be any string values, but they must not conflict with the standard ENVI header keywords. See ENVI Header Files for a list of these keywords.





The file ID (FID) is a long-integer scalar with a value greater than 0. An invalid FID has a value of -1. The FID is provided as a named variable by any routine used to open or select a file. Often, the FID is returned from the keyword R_FID in the ENVIRasterToFID routine. Files are processed by referring to their FIDs. If you work directly with the file in IDL, the FID is not equivalent to a logical unit number (LUN).


This is a case-insensitive string with the name of the user-defined keyword.

PRECISION (optional)

Use this keyword to specify the number of digits to the right of the decimal point when saving floating-point, double-precision, and complex data types for user-defined header values. The default is to use four decimal places.

Note: Be careful not to lose precision since the header values are stored as ASCII strings.


Set this keyword to store the output string in scientific notation rather than standard floating-point notation.


Use this keyword to specify the user-defined keyword values. VALUE can be a single element or an array of byte (8 bits), integer (16 bits), long integer (32 bits), floating-point (32 bits), double-precision floating point (64 bits), complex (2x32 bits), string, double-precision complex (2x64 bits), unsigned integer (16 bits), unsigned long integer (32 bits), long 64-bit integer, or unsigned long 64-bit integer values.