Similar previous discussions about this:
http://www.mozdev.org/pipermail/adblock ... 00145.html
In 2008, adp introduced "$third-party" filter, so scripts from other domains may be blocked, and I believe this is very good start. In reality however, many sites put their own resources under subdomains with similar names, i.e. "www.a.bbc.example.com" may include scripts from "b.bbc.example.com". Treating the later domain as external may break things, and $third-party filter is inappropriate here.
Noscript has something called "base 2nd level domains". It is not perfect applicable as pointed out in the above link, but it certainly gives a nice direction.
I'm thinking about adding a numerical parameter, such as "$third-party=1", to get a fine-grained control of the level of "externality". For example, given a site "www.a.bbc.example.com", applying
$third-party=0 allows "www.a.bbc.example.com" (current behavior)
$third-party=1 allows *.a.bbc.example.com
$third-party=2 allows *.bbc.example.com
$third-party= -1 allows *.com
$third-party= -2 allows *.example.com (which is the behavior of "2nd level domain" in Noscript)
Is this option possible to be implemented?