If holding and holding pattern entry procedures have not been published orif the procedures are not known to the pilot-in command of an aircraft, the appropriate ATC Unit shall describe the procedures to be followed. 

Aircraft shall be held at a designated holding point. The required minimum vertical, lateral or longitudinal separataion from other aircraft, according to the system in useat the holding point, shall be provided.

whne aircraft are being held in flight, the appropriate vertical separation minima shall continue to beprovided between holding and en-route aircraft while such en-route aircraft are within five minu

Instructions to an aircarft to hold and expected approach time shall be issued in the following circumstances :

   a) for an approach sequence;

   b) when it is mecessary to specify an intermediate clearance limit on the route to destination         aerodromes;

   c) for separation purposes, it is required to hold an aircraft over an en-route navigational fix;

   d) when due to traffic, holding is required over the last radio fix serving the destination aerodrome;

   e) when due to other causes, e.g runway being obstructed by disable aircraft, holding is required; or

   f) when due to adverse weather at destination aerodrome, aircraft is holding for weather improvement.