Bracket
A Bracket is a Market Profile concept.
A Bracket is viewed as a column of identical letters that has been formed while creating a Market Profile. Once the letters are collapse against the left margin they no longer appear in the same column.
Typically a bracket will be formed over a half hour period but the first bracket in some markets may not be half an hour if that market does not open on the hour or half hour.
A Bracket has a high and low and some traders also track the open and close of the bracket using different letters. A Bracket can be thought of as a bar on a bar chart without the open and close markers.