Here is a link to the "approvable letter" sent to Insmed back in September 2005. I use that term because that is how the FDA has the letter labeled in its files.:
No where in the letter does it state a "class" for the decision. In fact, I have not been able to find that information in any of the documents for the Insmed NDA. What I do see is that the FDA gave 10 days for the company to inform the agency of what action would be taken. The FDA then gave up a thumbs up to the proposed action and a new PDUFA date set. I remember the Insmed cc regarding the approvable notice and Geoff Alan stating that the response time would be quick but that he a classification had not been given -- people were skeptical about his "evasiveness" but he was being honest.
Maybe the FDA is not as upfront or straightforward as one would hope. It appears that there is a time period between the receipt of the "approvable letter" and the FDA's decision as to its classification.