1.DBG> DEFINE/VALUE COUNTER=0
      DBG> SET TRACE/SILENT R DO (DEFINE/VALUE COUNTER = COUNTER+1)

      In this example, the DEFINE/VALUE command assigns a value of
      0 to the symbol COUNTER. The SET TRACE command causes the
      debugger to increment the value of the symbol COUNTER by 1
      whenever address R is encountered. In other words, this example
      counts the number of calls to R.

    2.DBG> DEFINE/COMMAND BRE = "SET BREAK"

      This command assigns the symbol BRE to the debugger command SET
      BREAK.