Is there a way to specify that a feed requires a login?

[Aleks Totic]

Hi,
is there a way for an Atom feed to specify that reading articles 
requires a login?

The reason why I've thought of this question is a problem in 
Thunderbird feed reader implementation. It tries to fetch & 
display full articles as HTML. For authenticated sites, if your 
login cookies are not there, you get back a login page. In 
Thunderbird there is no way to fill in the login page, as all 
browsing requests are redirected to Firefox.

One solution might be to allow browsing and cookies inside 
Thunderbird only for logging into feeds. To implement this, and 
show the login button only when needed, tb needs to know that 
feed requires web-style authentication. Is there a way to specify 
this in Atom?

Similar problem arises in feed agregators. For example, flickr 
feeds might differ depending on your login status (whether you 
are friends or family...)

I've grep'd through the drafts, and the mailing list digest, but 
I have not found any discussion of this issue.

Aleks