This document gives guidance on specifying required dependability requirements and collating these requirements in a specification, together with the means of assuring the achievement of those requirements. The guidance provided includes: " specifying quantitative and qualitative reliability, maintainability, supportability and availability requirements; " advising purchasers on how to ensure that the requirements will be fulfilled by suppliers; " advising suppliers to help them meet the purchaser s requirements. Other obligations, such as legislation and governmental regulation may also place requirements on items and these should be applied in addition to any requirements derived in accordance with this standard. Whilst mainly addressing system and equipment level dependability, many of the techniques described in the different parts of IEC 60300 can also be applied to products or at the component level. The term item is used throughout this standard. NOTE 1 This guide does not directly consider safety and environment specifications although much of the guidance in this standard could also be applied to them. NOTE 2 This guide does not consider the specification of the dependability of a service, including those provided through Public-Private Partnership procurements. NOTE 3 The guidance in this document may be applied to some aspects of the specification of requirements relating to software but specific guidance may be found in IEC 62628 and the different parts of IEC 61508.