We're hearing Theta Protocol in Marvel's Agents of S.H.I.E.L.D. TV series for some time (Coulson was hiding it from the team). In the last episode S02E19 of the TV series, this conversation happened regarding Theta Protocol:
Maria Hill: Last Thing. Theta Protocol. Is it ready?
Coulson: Yes, it is. Time to bring in the Avengers.
What exactly is Theta Protocol? This clearly sets up the events of Avengers: Age of Ultron movie (which I have already watched), but I am unable to find a picture of Theta Protocol in the movie.