SURANGE - get max and min values for non-zero header entries 

 surange <stdin                               

 Note: gives partial results if interrupted                


 Credits:
      SEP: Stew
      CWP: Jack

 Note: the use of "signal" is inherited from BSD days and may break on some UNIXs.  It is dicy in that the responsibility for program termination is lateraled back to the main.