This question is specifically related to main options B and D where the ‘Prices’ is determined by reference to a Bill of Quantities (BoQ).
Clause 60.4 applies where the stated bullet point tests are satisfied, including where it is not due to a change to the Works Information / Scope. This can only be assessed once the final total quantity of work done is known.
Clause 60.6 relates to 3 types of ‘mistakes’ in the BoQ, as follows;
- departures from the rules for item descriptions,
- division of the work into method of measurement items,
- ambiguities or inconsistencies.
Each of these corrections is a compensation event, regardless of the reason why, although can be assessed as and when the issue is known and doesn’t rely on the final total quantity of work done.
As you have said, a ‘final total quantity’ difference may be due to an ambiguity or inconsistency, which if this is the case then the matter could be assessed under clause 60.6, rather than having to comply with the tests under clause 60.4, unless the resolution required a change to the Works Information / Scope, in which case it would be assessed as a 60.1 (1) compensation event.
Clause 60.7 means that the BoQ is used as the ‘starting point’ of a corresponding compensation event assessment, with the Employer / Client having responsibility for this being correct rather than the Contractor having any such liability. This principle applies in a similar way to that of a ‘physical condition’ compensation event and the interpretation of Site Information under clause 60.3. I would suggest that clause 60.7 applies to a compensation event assessment under clauses 60.4, 60.5 and 60.6.