这个问题的答案并不在程序里，而是在系统章节的相关 Normal Operation 中，个人觉得至少应该有个 “Ref to”，否则根本想不到。
具体请参考 TechRequest 原文：
Q:
In SOP of PARKING, there's fuel check with the description:
Check that the sum of the fuel on board and the fuel used is consistent with the fuel on board at departure. If the flight crew detects a discrepancy that is not usual, maintenance action is due.
How to determine "not usual"?
A:
A “not usual” discrepancy is determined by the same SOP fuel check than in cruise, when the flight crew compares the quantity of fuel used versus the quantity of fuel that is no longer in the fuel tanks. This check is described in the FCOM/Aircraft Systems/28-Fuel/Normal Operations/(FOB+FU) – BLOCK:
As a result, a discrepancy above +/- 1 200 kg (2 600 lb) should be considered as “not usual”.
