Training as deemed necessary by an ATO (could be nothing). SEP skills test with an examiner.
This can be found in FCL.740. It should come just before the revalidation requirements, which are in FCL.740.A The flight test is referred to in FCL.740 as a 'Proficiency Check'.
Rest assured, it's not just in Italy that people are more than 'a bit vague' on this.
MJ
