I've just finished my Erasmus period in the Netherlands. I'm still waiting for one result from my guest academy, then the Transcript of Record will reach my home university and, somehow, the results will be translated from Netherlands marks to Italian marks.
Is there an Erasmus standard on how to predictably translate results between ranking systems?
As far as I know, the translation is up to the universities who do the conversion. I think that it is unlikely that there are is one set of guidelines as even within a country not all universities have necessarily the same ranking systems.
I have found this table on Google though that gives some idea on what grades are roughly equivalent.