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I think I've tracked down the discrepancy.
EASA OPS Part-CAT (status is a CRD) says at AMC1-CAT.OP.AH.110 Aerodrome operating minima paragraph 4:
"The values in Table 5 should be derived from the formula below,
Required RVR/VIS (m) = [(DH/MDH (ft) x 0.3048) / tanα] - length of
approach lights (m)
where α is the calculation angle, being a default value of 3.00° increasing in
steps
of 0.10° for each line in Table 5 up to 3.77° and then remains constant."
In other words it looks like a line was omitted from the EU-OPS text. And indeed table 5 is consistent with the use of:
DH.........α
200-210 3.0
211-220 3.1
221-230 3.2
231-240 3.3
241-250 3.4
251-260 3.5
261-280 3.6
281-300 3.7
301+.....3.77
But that simply demands the question "why is α chosen like that?" Surely the nominal glideslope is 3 degrees??