What does the pragma <magritte-container> mean?

Sorry I've seached the net but I still do not know what this pragma is for. Can anyone shed some light on it? A related question: in the MagritteMagicExample (which seems to be the only Example available for Magritt3 one can find: talkJson: talkTitle <get> <produces: 'application/json'> <path: '/talk?title={talkTitle}'> | talk | talk := self talkFromTitle: talkTitle. self requestContext respond: [ :response | response contentType: WAMimeType applicationJson; nextPutAll: talk asJson ] So it seems this should produce come Json format. Does that work for anyone? Regards Friedrich