I checked the book and the inflight start limit is 650C.For engine start,the red line is at 535c until the engine reaches idle whereupon it changes to the 650c limit.Regarding why to keep the engines at T/O setting beyond 5 mins versus what normally happens,I go with LEM's reply.We know that climb power is set way before 5 mins,and that it is below max con most of the time,but its a matter of normal ops versus can it be done?Haven't managed to get in touch with the local Boeing rep,and will try to get a reply unless someone beats me to it.I asked around about the 5/10min limit and seems to be limited to the machines with two motors.