Positioning of players during technical foul free throw

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By convention, officials require players other than the technical foul shooter to be at or near the division line while free throws are administered. However, I cannot find reference by rule or guidance in officials manual where the other players are required to be. As a former official, I am interested in the exact rule/requirement. As a current coach, I see an advantage of having my players close enough to the coaching box to talk to them if the rules allow it. Can someone help out?