$R.                      Range Checking                          Default: $R-

{$R.}

    Enables generation of range checking code, which will check all array
    indexing operations for boundary violations, and also check all
    assignments to scalar and subrange variables for range violations.

             $R+    Generate code to check index, scalar, and subrange
                    values.

             $R-    Disable range checking.

          Range:    From current location to next $R. directive.