A single bracket is used to enclose the ending of a long line of poetry which will not fit the register and has to be run over into an adjoining line.
Doubt whether to use parentheses or brackets can usually be settled by this general principle: Parentheses always enclose remarks apparently made by the writer of the text.

Brackets enclose remarks certainly made by the editor or reporter of that text.
THE INTERROGATION The interrogation is the point that asks questions.

It should always be placed outside quotation marks unless it is a part of the quotation itself.
_Rules for the Use of the Interrogation_ 1.

The interrogation point is used at the end of every direct question.
Are you there?
Indirect questions, that is, statements that a question has been asked, do not require the interrogation.
He asked me if I was there.
He asked the question, Are you there?
and received no answer.
2.

At the end of each of a series of questions thrown into a single sentence.
Did he speak in an ordinary tone?
or shout?
or whisper?
3.