I'm documenting my api with Apiary and I'm using the old syntax of the blueprint.
I read somewhere about the separation of different responses with "+++++", but I do not know how to tell when apiary to use my first or second response.
This is currently not possible, first response is always used.
Support for this will be landing soon, based on status code, content type and prefer header match. See http://support.apiary.io/forums/120125-general/suggestions/3264498-match-on-request-headers for more details.