anchor.diff:          let branch = tag.Substring(0, idx)
           let version = tag.Substring(idx+1)
           { TagInfo.BuildBranch = branch; TagInfo.BuildNumber = version }
  -        
  +
   
   // =====================================================================================================
   
  
positive.code: 
  // =====================================================================================================
  
  [<Sealed>] 
  type Factory(graph : Graph) = class end
  with
      let wsDir = Env.GetFolder Env.Folder.Workspace
  
negative.code: 
      member this.IsHead = isHead
  
      member this.Bookmarks : Bookmark set =
          collectBookmarks()
  
      static member (-) (ref : Baseline, target : Baseline) : Bookmark set =
  