It seems that the "final reserve" fuel carried in an aircraft under the new part 91 Manual of standards is never to be used. If you are ever caught with less that the specified reserve in your tanks then you are a criminal. Moreover, you are required to self incriminate.
Thsi requirement also automatically allows your arriving fuel state to be inspected as part of a ramp check.
This section is for paragraph 91.320 (1) (d) of CASR
— procedures to be followed if fuel reaches specified amounts during a flight.
(2)If an in-flight fuel quantity check shows that usable fuel on arrival at the destination aerodrome would be less than:
(a) the required alternate fuel plus final reserve fuel — the PIC must:
(i) having taken into account the traffic and operational conditions likely to be prevailing on arrival — plan for a safe landing at the destination aerodrome, the destination alternate or another en-route alternate; and
(ii) proceed to whichever of those aerodromes will enable the PIC to perform a safe landing with not less than final reserve fuel remaining; or
(b) the final reserve fuel (where no alternate aerodrome is required) — the PIC must proceed to an en-route alternate aerodrome which will enable the PIC to perform a safe landing with not less than final reserve fuel remaining.
(3)The PIC of a radio-equipped aircraft must advise ATS of a “Minimum fuel” state if, having committed to land at a specific aerodrome, the pilot calculates that any change to the existing clearance to that aerodrome may result in landing with less than the final reserve fuel.
(4)If the calculated usable fuel predicted to be available upon landing at the nearest aerodrome where a safe landing can be made would be
less than the final reserve fuel, the PIC of a radio-equipped aircraft must declare to the ATS a fuel emergency by broadcasting “MAYDAY, MAYDAY, MAYDAY FUEL”.
Note The fuel emergency declaration is a distress message