Ready, Set, go--Ladder items must go, too full

[Crystalion]

Having no other thread to put this question...How does one get rid of the whole "Expires in 10 days" thing on one's ladder characters?  ...
In short: How does the "Expires in 10 days" thing work?

Take a look at the posts (non-threaded) in the last half of the second page of this LL thread: some people's comments on burning in Mules.

Basically it seems to kick idle characters out (but less so if more than one character is in the game) after a while. Being alt-tabbed out is okay in general. And the time needed for "permanent" status is apparently accumulated across sessions, as you can indeed gain that status piecemeal.