BS ISO 20107:2015 pdf download

BS ISO 20107:2015 pdf download.Space data and information transfer systems — Spacecraft onboard interface services — Device virtualization service
1.5.1.1 General
For the purpose of this document the following definitions apply.
1.5.1.2 Definitions from the Open Systems Interconnection (OSI) Basic Reference Model
This document is defined using the style established by the Open Systems Interconnection (OSI) Basic Reference Model (reference [D2]). This model provides a common framework for the development of standards in the field of systems interconnection. The following terms used in this Recommended Practice are adapted from definitions given in reference [D2]: layer: Subdivision of the architecture, constituted by subsystems of the same rank. service: Capability of a layer, and the layers beneath it (service providers), provided to the service users at the boundary between the service providers and the service users.
1.5.2 TERMS DEFINED IN THIS RECOMMENDED PRACTICE
For the purposes of this Recommended Practice, the following definitions also apply. application: Any component of the onboard software that makes use of the Device Virtualisation Service. This includes flight software applications and higher- layer services. NOTE – Such components include flight software applications and higher-layer services. device: Real hardware component of the spacecraft or a single register within such a component. NOTE – Examples of such components are sensors and actuators. timestamp: Time associated with a value. NOTES 1 The format of a timestamp is implementation-specific. 2 The timestamp may indicate the time the value was generated by the device, emitted by the device or acquired by the service. This is implementation-specific.
1.6 NOMENCLATURE
1.6.1 NORMATIVE TEXT
The following conventions apply for the normative specifications in this Recommended Practice:
a) the words ‘shall’ and ‘must’ imply a binding and verifiable specification;
b) the word ‘should’ implies an optional, but desirable, specification;
c) the word ‘may’ implies an optional specification;
d) the words ‘is’, ‘are’, and ‘will’ imply statements of fact.
NOTE – These conventions do not imply constraints on diction in text that is clearly informative in nature.
1.6.2 INFORMATIVE TEXT
In the normative sections of this document, informative text is set off from the normative specifications either in notes or under one of the following subsection headings:
– Overview;
– Background;
– Rationale;
– Discussion.
1.7 REFERENCES
The following publications contain provisions which, through reference in this text,constitute provisions of this document. At the time of publication, the editions indicated were valid. All publications are subject to revision, and users of this document are encouraged to investigate the possibility of applying the most recent editions of the publications indicated below. The CCSDS Secretariat maintains a register of currently valid CCSDS publications.