After each question, both candidates get two minutes to respond. Crowley will then ask a follow-up question. The candidates will have another two minutes total to discuss, but that time can be extended at Crowley's discretion. The Presidential Debate Commission is hoping to get through 13 questions.
Both campaigns objected to Crowley's intention to ask follow-up questions, having agreed themselves that she would not do so. But that agreement did not include Crowley or the commission.
In all, there will be 82 town hall members on the stage. Only Crowley will know the questions in advance. The town hall participants have already submitted their questions to her. With a small team of helpers, she's chosen the people who will get to speak and the order in which they will do so.