The Return Input Line routine returns to the caller the requested
    line from the recall buffer. This line is retrieved either
    by matching it with a specified string or by specifying the
    appropriate line number.

    Format

      SMG$RETURN_INPUT_LINE  keyboard-id ,resultant-string

                             [,match-string]

                             [,byte-integer-line-number]

                             [,resultant-length]