This is a mirror of http://www.vim.org/scripts/script.php?script_id=2987

When you open a file, it searches for tags files in all ancestor directories and loads them. This is useful when you work on several projects and have different set of tags for each of them.

Let's say that you open file /home/user/projects/my_proj/lib/hello.pm. Loadtags plugin looks for files 

/home/user/projects/my_proj/lib/tags, 
/home/user/projects/my_proj/tags, 
/home/user/projects/tags, 
/home/user/tags, 
/home/tags, 
/tags 

and calls setlocal tags+= on those that exist.