The SET statement sets values of indexes associated with table
  elements.  It can also change the value of a conditional variable,
  change the status of an external switch, and store the address of a
  COBOL identifier reference at run time.

  Format 3 -

   SET { cond-name } ... TO TRUE

1  –  cond-name

  is a condition-name that must be associated with a conditional
  variable.