This routine replaces an existing record in the file. It has four parameters: file_handle, record, length, and keyval.
|file_handle||must be a valid file handle returned by R-OPEN-FUNCTION.|
|record||is the record data to write to the file.|
|length||is the number of bytes to write (for variable-length files).|
|keyval||is the record number to write. A keyval of -1 means to write at the end of the file.|
The R-REWRITE-FUNCTION routine does not change the current file position.