Hi, Concerned with the answers to the [that topic](http://www.ntg.nl/pipermail/ntg-context/2014/077099.html), I was thinking if I could define a command "Exercise" with a optional argument (the "Answer"). \defineblock[question] \defineblock[answer] \defineenumeration[question][text={Question}] \defineenumeration[answer] [text={Answer}] \keepblocks[question] \hideblocks[answer] Something like \startexercise My execise ... \stopexercise If no more is provide, at the question does \incrementcounter[answer] If \startexercise{\startsolution The solution is \stopsolution} My exercise \stopexercise then \beginanswer and \startanswer is called. Is it possible? I just want to know if it's better to have \startBla...\stopBla command or \Bla{} command type? In the case of the first, how do you define that? I did not find it here (http://wiki.contextgarden.net/Commands_with_optional_arguments) Thanks, Xan PS: Please CCme