The repair of Defects (corrective maintenance) has to be done at different levels. For the sake of Equipment availability, repair on the Equipment is done by exchanging (Level 1 maintenance) the defective Goods, subassembly or component (LRU). The repair of this defective LRU itself (Level 2/3 maintenance) shall then be done off-line in a workshop.The Supplier shall supply a Defect Finding Guide in Preventive and corrective maintenance instructions which allows the Defect diagnosis of the Goods within the supplier's scope of supply, down to the replaceable unit that has caused that Defect. The detail of information shall be sufficient to allow this diagnosis to be completed within 1 hour by a train maintainer."