I wonder if the CAA intended to make the 500/600ft limits mandatory, but actually the wording of the ANO 2000 failed to do so? Thus they are in the position where they wish it was mandatory, they intended it to be so, they would like us to believe so, but when you put them on the spot they have to admit that it's not?
I have to admit that DFC's case is coherent - the training syllabus, the test standards, the written exams all hang together - but there is the undeniable fact that the CAA have told people the limits are advisory.
Tim