Open Procedure Pursuant To Art. 71 Of Legislative Decree 36/2023 And S.M.I., Preparatory To The Stipulation Of N. 9 Framework Agreements With A Single Economic Operator Ex. Art. 59, Paragraph 3, Of Legislative Decree 36/2023 For The Duration Of 36 Months With Effect From The Date Of Stipulation, With The Possibility Of Extension Of An Additional 6 Months, In Order To Guarantee The Management, Maintenance And Re Service Service