5.2.2 Maintenance or support of a computer`s operating system; 8.18 Perle to notify immediately if the hardware and software need to be maintained or do not function properly. “Hardware” means the computer equipment set forth in the Appendix and additions and modifications agreed from time to time in writing between Parties 2.1.4 The Customer is responsible, at its own expense, for returning to the Authorized Service Center the equipment required by the Maintenance Services. The customer ensures that they are packed in the packaging supplied with the spare parts or material, and that this packaging is clearly marked by the RMA code provided by Perle. During the currency of this Agreement, Perle provides (subject to clause 5) one of the following categories of maintenance services with respect to material defects reported by the customer in accordance with clause 2.3. . .