The number assignment for billing documents in Italy is carried out chronologically and in ascending order. For example, billing document number 92000045 cannot be assigned on May 2, 1996 and then billing document number 92000044 on May 3, 1996.
In Italian companies, there is normally a person in charge who determines what the next billing date will be by making a corresponding entry in a table. You can perform this activity by first choosing the menu options Logistics -> Sales/distribution -> Billing and then Environment -> Set billing date .