Allows you to add explanatory text to code. The comment begins with /* and ends with */. This type of comment can wrap over multiple lines.
The r-comm.p example uses comments to document the history of procedure modifications.
r-comm.p
| /* Procedure written  9/5/87 by CHC
             revised  9/27/87 by DG */
FOR EACH Customer NO-LOCK:
  DISPLAY Customer.CustNum Customer.Name Customer.Contact Customer.Phone.
END. | 
The r-comm2.p example uses comments to describe what the procedure does.
r-comm2.p
| /* Step through unshipped orders */
FOR EACH Order NO-LOCK WHERE Order.ShipDate = ?:
  /* Display order date, promise date, terms */
  DISPLAY Order.OrderDate Order.PromiseDate Order.Terms.
  /*
    FOR EACH OrderLine OF Order NO-LOCK:
      /* Display all OrderLines of each Order */
      DISPLAY OrderLine.
    END.
  */
END. | 
The comment symbols that enclose the inner FOR EACH block turn that block into a comment for testing purposes. You can nest comments, so ABL correctly processes any comments already in the bypassed code. Both multi-line comments and single-line comments can be nested inside a multi-line comment.