To what extend does Robots Meta Tags affect backlinks?Conside this scenario

A Website 'A' has a backlink from Website 'B' however, the backlink appears on a page using a robots meta tag with "Index, Nofollow". Google advises that Website 'B' provides a link to Website 'A' so it has indexed the URL, but what about the value of the backlink from such a page compared with one with no robot restrictions ?

That sites with backlinks from quality sites are given extra weight is well known but does google simply count the backlink as a 'vote' for Website 'A' or whether, in addition, it analyzes the content of the target page (and perhaps more) for relevancy before adding weight?

For further discussion,check the discussion highrankings.com/forum/index.php?showtopic=35873