I've not been on the orchestra but have frequently cruised with MSC and the same rules seem to apply on all their fleet, They have 3 dress codes formal, informal and casual. Dont know how long the cruise you are going on so a 7 night would have 2 formal, 10 or 11 night 3 formal, 19 night 5 formal nights. Formal means Evening or cocktail dress for ladies, tuxedo or longe suit for men. Informal is dress or other less formal evening wear, me suit (without tie or dress shirt and slacks without tie, casual is what it says. MSC get quite a mixed age range and you will find quite a variation in what people wear for all 3 types of dress code. Hope this help.