The %whex() function writes to the file specified by file.descriptor returned by a previous call to %open(), %creat(), or %dup() a string of bytes resulting from converting the ASCII string variable into binary.
byte.count = %whex(file.descriptor, var)
Two digits are converted into one eight bit binary character. var is assumed to contain only hexadecimal characters 0 to 9, A to F or a to f. The function returns the number of bytes actually written or -1 if an error occurred. The size written to the file is the size of var divided by 2. This function is the reverse of %rdhex().
* Write "eof"x’ff’ on device
n=%whex(fd, oconv("eof","mx"):’FF’)