I would guess that it's there to ensure that those who are dealing with 261/2004 claims have a quick pointer to whether to accept or refuse the claim. Sometimes, FTers seem to have unrealistic expectations of the amount of time and energy that any particular staff member can devote to dealing with their 261/2004 claim. I imagine that such staff are under tremendous pressure to make quick decisions, whether those are "yes" or "no". As in so much else, that would go a long way to explaining the rubbish answers that are sometimes given when the response is a "no". Conversely, if the staff member sees the code "OPEY", they will say "yes" and move on to the next 261/2004 claim inside 5 minutes. It seems to me that it would be naive to think that each application has an hour or two of a single staff member's time devoted to it while they investigate all of the ins and outs of what happened that day, but some people seem to think that this is what ought to happen.