The 'actuate' attribute is used to communicate the desired timing 
of traversal from the starting resource to the ending resource; 
it's value should be treated as follows:
onLoad - traverse to the ending resource immediately on loading 
         the starting resource 
onRequest - traverse from the starting resource to the ending 
            resource only on a post-loading event triggered for 
            this purpose 
other - behavior is unconstrained; examine other markup in link 
        for hints 
none - behavior is unconstrained