We dont normally go into specifics ..that said ..I have around two hundred names ( non .fr ) with them (via their blue razor service and have done so for around 5 years now ..I trust them ..prior to that I was with someone else )..and have never been notified by them that someone wishes to "back order"..then again mine are all set to auto renew ..so ..
Normally after expiration the owner has around a week to 15 days to renew at the standard price ..then upto 90 days "redemption" period ..during which they can still keep the domain ..but the fee is higher ..
If they still dont do anything after that time ..then the domain can either go back onto the open market ..or the registrar may put it to auction ..depends on the registrar ..
Which is why if you really want it ..you "back order" with the "current registrar" so as to have the best chance of "catching" it if it "drops" ..
Lots of threads you can search [webmasterworld.com] for using the terms I've placed in "quotes" in the past here about how this works with various registrars and in general.
Normally if the domain expires on March 1st ..someone else cannot try to get it until at least 90 days have passed ..