Yes, I can, and I may ask Terry to complement my answers.
An ACAN is not a sole-source contract; it's an RFP with a twist, that's all it is. Once a client department on the Hill has identified a need for a particular asset--it's not just the military, it could be any other department--and that department is convinced that there's only one manufacturer of that particular asset, and we at Public Works feel they are right—we have a good understanding of the industry, and so does the client department in terms of the supply chain—then we issue an ACAN. This tells the world that we think that for these glasses, there's only one manufacturer, we believe this is the manufacturer, and unless we hear otherwise within the next 15 to 30 days, we're going to go into a negotiation to award a contract to the manufacturer of the glass.
It is a form of RFP, but it's one step further in the sense that you've already identified which manufacturer you believe is the only manufacturer to produce the goods in question.