From
2014 Airspace & Safety Initiative (ASI). so may not necessarily be authoritative:
A Procedural Service is a non surveillance service in which deconfliction advice is provided against other aircraft in receipt of a Procedural Service from the same controller. The avoidance of other aircraft is the pilot’s responsibility.
It would seem that mad_jock is correct but, for me, that then raises another question:
Why do Controllers use the phrases: "
Cleared to enter the Hold", "
Cleared for the ILS procedure", etc?