<p>We've been using Scrum on a few projects now with varying success and I now have a query relating to documentation.</p>

<p>In Scrum, you obviously have the product backlog ("The application begins by bringing up the last document the user was working with.") and the sprint task backlog ("Implement forgot password screen").  However, in all the examples I have seen, these two items are fairly high level in terms of detail (being designed on fit on a post-it note).</p>

<p>So, where does the detail sit?  Let's say the client has some very specific requirements for a stock management screen, or has a complex API that needs to be integrated with on the back end, where is this documented, how and who captures this information?  Is it seperate to the backlog but populated on a just-in-time basis or some other way?</p>

My understanding is that specific requirements such as this are handled by the product owner. They will liase with the client during Sprint Planning 2 and update the tasks with specfic requirements as needed - hence why the Product Owner is a optional attendee of the Sprint Planning 2 meeting. This gives you a hybrid of Just-in-Time and Sprint Planning 2 population of the specifics. Anything that isn't satisfied by the time you come to work on the task will be an impediment and should be dealt with a the daily scrum, by the product owner.
As the development is Agile when using Scrum you shouldn't find too much of an issues getting requirements just in time.