title: Cobol open input file error message
body: <p>What is the error handling command for open input line-sequential file?</p>
  
  <p>I tried,</p>
  
  <pre><code>OPEN INPUT CUSTOMER-FILE
  INVALID KEY/ON ERROR
  DISPLAY "NO FILE FOUND".
  </code></pre>
  
  <p>but could not get it to work.</p>
  
  <p>Thanks.</p>