Strictly speaking by the contract, it is what is listed in Charges 41.
The issues come when interpreting that. As a real life example - and there are others - when it says in the 3rd bullet “payments for … services for … security” does this mean for the hire costs of security infrastructure e.g. movement detectors, security lights etc or does it also include the cost of security person (or are they paid for directly as a Subcontractor or under People).
Even if you arrive at a definitive view on this, there is then the question of where you pitch it. At one extreme, do you assume all compensation events have a time-related aspect and therefore the people percentage needs to take account of this (but that might make you un-competitive at tender) or, at the other extreme, no time-related effects, which means you might well lose money on compensation events which have an affect.
Although not the official reason given, this is probably the main driver for removing it from the fourth edition with things just being paid for at cost.