What does "Recent" mean in Recent Unread Posts?

[#1]

I know this isn't really a bug or suggestion, but I would like to know what "Recent" means in "Recent Unread Posts" http://community.plus.net/forum/index.php?action=unread
How is it calculated?  Is it unread posts made in the last x days?  And if so, what is x?
A few days ago I had an empty list when I clicked "Unread posts", even when I then clicked "All unread topics".  I know I've never read everything, so how is this possible?  I don't "mark all as read".
Martin

[#2]

Firstly they only work if you are logged in (a mistake make by some people).
Recent Unread Topics are those with new posts since the last visit in your previous browser session. When you first enter the forums and log in it will show everything since that last visit as new. If you leave the forums to visit other websites but keep the browser open, when you return the new posts which you hadn't read will still show as new. If you close the browser and go back in this will start a new session so all the posts which were showing as new in Recent Unread Topics will no longer appear in that list, they will however appear in the All Unread Topics list.
Just to complicate it further, the selection you make on the login page will also affect it. If you chose Minutes to stay logged in, and that long elapses in the current browser session without you visiting the forums it will be the same as if you closed the browser.
I find it works well if you use the Always stay logged in option.

[#3]

Thanks jelv, for clarifying????! 

[#4]

if you want to see all unread postings  (I have just come back from Hols), after you have clicked unread post, then click, show all unread posts, then if you click on the date column you can see the oldest first  -  I only have 12 pages to look at, even after clearing the forums I dont like !!!!!!