Thanks for the useful link, Selfin.
However in this WMO FM 51 about TAF's, I can't find anything about these 6-group icing forecast. Therefore I supposes that is not international but country specific. Apart from Russia, which other countries use it? Anyone?
Thanks,
Sabenaboy
PS: could it be that MrBernouillie was confusing this 6-group with a 8 figure RSM himself in his reply nr 6?