Yellow Hatting in the Six Hats, Six Coats metaphor is about the contextual perspective of a system. Edward de Bono does not have a hat for this perspective.
Yellow Hats take the conceptual design provided by the Green Hats and look for the niche market. In the Yellow Hat perspective designers evaluate goals, networks, data, processes, people and times that require products or services within the conceptual domain. Yellow Hat contextual design is used by the White Hat logical design team.
Like the other hats, the Yellow Hat is worn with each of the Six Coats. The basic question is what is the most unique product or service we can make available within the conceptual domain.
Yellow Hat, Green Coat: What is our unique product or service mantra?
Yellow Hat, Yellow Coat: Where are we navigating?
Yellow Hat, White Coat: Where is our data?
Yellow Hat, Black Coat: Where are our processes?
Yellow Hat, Red Coat: Where are our personas?
Yellow Hat, Blue Coat: Where are we convenient?
Yellow Hat also has a reverse purpose when variances occur in the transacting system. Yellow Hats decide how to handle a deviation which is to select a new product or service for the system to accomodate the exception or to escalate it up to the Green Hats.