Presumably 'direct fork' repos can be added to teams.

richardkmichael · richardkmichael · commit a712a275959c · 2013-03-22T14:06:00.000+01:00
diff --git a/content/v3/orgs/teams.md b/content/v3/orgs/teams.md
@@ -190,7 +190,7 @@ NOTE: This does not delete the user, it just remove them from the team.
 
 In order to add a repo to a team, the authenticated user must be an
 owner of the org that the team is associated with.  Also, the repo must
-be owned by the organization, or a direct form of a repo owned by the
+be owned by the organization, or a direct fork of a repo owned by the
 organization.
 
     PUT /teams/:id/repos/:owner/:repo
