This general and guidance document provides an author of new product specification in the series EN 50411-2-X rules and conventions under which a closure interface is created, and provides a consistent structure: - headings; - format; - abbreviations; - definitions; - references; - descriptions; - document structure details; - tables; - diagrams; - dimensions; and - product variants. This general and guidance document provides general information that defines the closure options, including the following: - level of sealing, sealed or non-sealed; - closure configurations, shape and/or entry port orientation; - 'fibre management system' or 'microduct' connectors contained within the housing; - cable port entry configurations, number of ports; - cable sealing method, heat or non-heat activated. In order to comply with the specification, the following closure and/or FMS requirements must be defined: - sealing and optical functionality; - physical dimensioning, giving the maximum outer perimeters for all sizes; - geometrical form and or shape; - dimensioning. The product specification should provide external overall dimensioning of closures to fit in their external location, e.g. underground chambers, street furniture or aerial applications. A fibre splice closure product specification includes both the parameters of the closure housing, the fibre splicing management system. These systems are always supplied together with the closure as a matched set including other functional or ancillary parts of an optical node. An air blown fibre closure product specification includes only the parameters of the closure housing, Air blown fibre closures are normally supplied without a microduct connector, largely because of uncertainty over connector method, microduct sizes, quantity and type of connector used. This closure specification allows single mode fibre to be used, and covers all IEC or EN standards of optical fibre cables as listed in the normative references with their various fibre, capacities, types and designs. For convenience the term "cable" in this document may refer to different types of optical fibre cable designs, including air blown fibre', 'protected microduct', or 'microduct'.