Grandagon versus Grandagon-N: both MC and 75mm 4.5

[J. P. Mose]

The late pre-N Grandagon's have "multi coated" stamped on the lens barrel. At s ome point Rodenstock added the -N on the Grandagon. What improvements did the G randagon-N 75mm 4.5 have over a Grandagon 75mm 4.5 multicoated (non -N)? The le ns formulas in photos appears to be identical. Any technical explanations out t here? Thanks.

Best regards,

J. P. Mose