I've been wondering lately about whether comparing link attributes in HTML code would provide any value to the search engines. Testing's been done by SEOs in the past about the value of link titles (minimal if any) and rel attributes other than nofollow (nada), but I'm wondering about the target attribute, specifically. Currently, according to W3C, you can assign:

• _blank - the target URL will open in a new window
• _parent - the target URL will open in the same frame as it was clicked
• _self - the target URL will open in the parent frameset
• _top - the target URL will open in the full body of the window

Since parent, self & top are all, largely on-site options, I'm thinking that "blank" is the only option that could have any real impact.

If I were a search engineer, I'd definitely test out whether assigning less value to (external) links that open in a new window produced better results. My guess is that it doesn't mean a thing, but I know there's some smart people posting in the comments here, so I'd love to hear what you've got to say.

p.s. Note on the W3C schools page, the "nofollow" attribute doesn't exist in the "rel=" options. :)