Foggy Albion native speakers, please help
How much "will" is mandatory in the following excerpt. Why is it not "shall" or "must"?:
When an aircraft is descended from a flight level to an altitude preparatory to commencing approach for landing, ATC will pass the appropriate QNH. On vacating the flight level, the pilot will change to the aerodrome QNH unless further flight level vacating reports have been requested by ATC, in which case, the aerodrome QNH will be set following the final flight level vacating report. Thereafter, the pilot will continue to fly on the aerodrome QNH until established on final approach. When requested by the pilot or local procedures require, the appropriate QFE and aerodrome or threshold elevation shall also be given. When carrying out a radar approach, ATC will assume that an aircraft is using QNH on final approach and will include a reminder of the appropriate QNH setting in the RTF phraseology. If the pilot requests to undertake the approach using QFE, then ATC will pass the appropriate QFE and “height” will be substituted for “altitude” in the RTF phra-seology. It should also noted that the Obstacle Clearance Height is always given with reference to the aerodrome or threshold elevation.
STATE RULES AND PROCEDURES - EUROPE 1495 UNITED KINGDOM RULES AND P
With my limited knowledge of English I may understand this as a kind of gentle request to follow a national rule which contradicts the ICAO standard. Am I right or does it have far more reaching legal implications? Is "will" a common word in your rules and do we have to follow whatever is after?