Suppose that $ M_t $ is a continuous martingale. I saw this notation in a newspaper: $ langle M rangle_t $ or $ langle M rangle_ infty $. What does this notation mean?
The paper does not explain the notation, so I suspect that it is known. I am aware that angle brackets are sometimes used to indicate expectation, but paper is used $ E M_t $ denote the expectation. Likewise, $ t $ is outside the parenthesis, which indicates that it is not an expectation notation. Does it refer to a particular notation used in martingales?