ISO 26143:2007

INTERNATIONAL ISO
STANDARD 26143
First edition
2007-02-15
Space data and information transfer
systems — Space link extension (SLE) —
Return operational control fields service
Systèmes de transfert des données et informations spatiales —
Extension de liaisons spatiales (SLE) — Service des champs de
contrôle de retour opérationnel

Reference number
©
ISO 2007
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2007
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2007 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 26143 was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as
CCSDS 911.5-B-1, November 2004) and was adopted (without modifications except those stated in Clause 2
of this International Standard) by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 13, Space data and information transfer systems.

INTERNATIONAL STANDARD ISO 26143:2007(E)

Space data and information transfer systems — Space link
extension (SLE) — Return operational control fields service
1 Scope
This International Standard defines the space link extension (SLE) return operational control fields (ROCF)
service in conformance with ISO 15396:1998. The ROCF service is an SLE transfer service that delivers to a
mission user all operational control fields from one master channel or one virtual channel.
This International Standard defines, in an abstract manner, the ROCF service in terms of
⎯ the operations necessary to provide the service;
⎯ the parameter data associated with each operation;
⎯ the behaviors that result from the invocation of each operation; and
⎯ the relationship between, and the valid sequence of, the operations and resulting behaviors.
It does not specify
⎯ individual implementations or products;
⎯ the implementation of entities or interfaces within real systems;
⎯ the methods or technologies required to acquire telemetry frames from signals received from a
spacecraft;
⎯ the methods or technologies required to provide a suitable environment for communications; or
⎯ the management activities required to schedule, configure, and control the ROCF service.
The scope and field of application are furthermore detailed in subclause 1.3 of the enclosed CCSDS
publication.
2 Requirements
Requirements are the technical recommendations made in the following publication (reproduced on the
following pages), which is adopted as an International Standard:
CCSDS 911.5-B-1, November 2004, Space link extension — Return operational control fields service
specification.
For the purposes of international standardization, the modifications outlined below shall apply to the specific
clauses and paragraphs of publication CCSDS 911.5-B-1.
Pages i to v
This part is information which is relevant to the CCSDS publication only.
Page 1-14
Add the following information to the reference indicated:
[1] Document CCSDS 910.4-B-1, May 1996, is equivalent to ISO 15396:1998.
[2] Document CCSDS 131.0-B-1, September 2003, is equivalent to ISO 22641:2005.
[3] Document CCSDS 132.0-B-1, September 2003, is equivalent to ISO 22645:2005.
[4] Document CCSDS 232.0-B-1, September 2003, is equivalent to ISO 22664:2005.
[5] Document CCSDS 732.0-B-1, September 2003, is equivalent to ISO 22666:2005.
[6] Document CCSDS 133.0-B-1, September 2003, is equivalent to ISO 22646:2005.
[7] Document CCSDS 301.0-B-3, January 2002, is equivalent to ISO 11104:2003.
[9] ISO/IEC 8824:1998 has been cancelled and replaced by ISO/IEC 8824:2002, Information technology —
Abstract Syntax Notation One (ASN.1).
Page E-1
Add the following information to the reference indicated:
[E4] Document CCSDS 102.0-B-5, November 2000, is equivalent to ISO 13419:2003.
[E5] Document CCSDS 202.0-B-3, June 2001, is equivalent to ISO 12172:2003.
3 Revision of publication CCSDS 911.5-B-1
It has been agreed with the Consultative Committee for Space Data Systems that Subcommittee
ISO/TC 20/SC 13 will be consulted in the event of any revision or amendment of publication
CCSDS 911.5-B-1. To this end, NASA will act as a liaison body between CCSDS and ISO.
2 © ISO 2007 – All rights reserved

Consultative
Committeefor
SpaceDataSystems
RECOMMENDATION FOR SPACE
DATA SYSTEM STANDARDS
SPACE LINK EXTENSION—
RETURN OPERATIONAL
CONTROL FIELDS SERVICE
SPECIFICATION
CCSDS 911.5-B-1
BLUE BOOK
November 2004
(blank page)
4 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
AUTHORITY
Issue: Blue Book, Issue 1
Date: November 2004
Location: Toulouse, France
This document has been approved for publication by the Management Council of the
Consultative Committee for Space Data Systems (CCSDS) and represents the consensus
technical agreement of the participating CCSDS Member Agencies. The procedure for
review and authorization of CCSDS Recommendations is detailed in the Procedures Manual
for the Consultative Committee for Space Data Systems, and the record of Agency
participation in the authorization of this document can be obtained from the CCSDS
Secretariat at the address below.

This Recommendation is published and maintained by:

CCSDS Secretariat
Office of Space Communication (Code M-3)
National Aeronautics and Space Administration
Washington, DC 20546, USA
CCSDS 911.5-B-1 Page i November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
STATEMENT OF INTENT
The Consultative Committee for Space Data Systems (CCSDS) is an organization officially
established by the management of member space Agencies. The Committee meets
periodically to address data systems problems that are common to all participants, and to
formulate sound technical solutions to these problems. Inasmuch as participation in the
CCSDS is completely voluntary, the results of Committee actions are termed
Recommendations and are not considered binding on any Agency.
This Recommendation is issued by, and represents the consensus of, the CCSDS Plenary
body. Agency endorsement of this Recommendation is entirely voluntary. Endorsement,
however, indicates the following understandings:

o Whenever an Agency establishes a CCSDS-related standard, this standard will be in
accord with the relevant Recommendation. Establishing such a standard does not
preclude other provisions which an Agency may develop.

o Whenever an Agency establishes a CCSDS-related standard, the Agency will provide
other CCSDS member Agencies with the following information:

-- The standard itself.
-- The anticipated date of initial operational capability.

-- The anticipated duration of operational service.

o Specific service arrangements shall be made via memoranda of agreement. Neither this
Recommendation nor any ensuing standard is a substitute for a memorandum of
agreement.
No later than five years from its date of issuance, this Recommendation will be reviewed by
the CCSDS to determine whether it should: (1) remain in effect without change; (2) be
changed to reflect the impact of new technologies, new requirements, or new directions; or,
(3) be retired or canceled.
In those instances when a new version of a Recommendation is issued, existing CCSDS-
related Agency standards and implementations are not negated or deemed to be non-CCSDS
compatible. It is the responsibility of each Agency to determine when such standards or
implementations are to be modified. Each Agency is, however, strongly encouraged to direct
planning for its new standards and implementations towards the later version of the
Recommendation.
CCSDS 911.5-B-1 Page ii November 2004
6 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
FOREWORD
This document is a technical Recommendation for use in developing ground systems for
space missions and has been prepared by the Consultative Committee for Space Data
Systems (CCSDS). The Space Link Extension Return Operational Control Fields Service
described herein is intended for missions that are cross-supported between Agencies of the
CCSDS.
This Recommendation specifies a data service that extends certain of the space-to-ground
communications services previously defined by CCSDS (references [2], [3], and [5]) within
the framework established by the CCSDS Space Link Extension Reference Model (reference
[1]). It allows implementing organizations within each Agency to proceed with the
development of compatible, derived Standards for the ground systems that are within their
cognizance. Derived Agency Standards may implement only a subset of the optional
features allowed by the Recommendation and may incorporate features not addressed by the
Recommendation.
Through the process of normal evolution, it is expected that expansion, deletion or
modification to this document may occur. This Recommendation is therefore subject to
CCSDS document management and change control procedures, as defined in the Procedures
Manual for the Consultative Committee for Space Data Systems. Current versions of
CCSDS documents are maintained at the CCSDS Web site:
http://www.ccsds.org/
Questions relating to the contents or status of this document should be addressed to the
CCSDS Secretariat at the address indicated on page i.
CCSDS 911.5-B-1 Page iii November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
At time of publication, the active Member and Observer Agencies of the CCSDS were:

Member Agencies
– Agenzia Spaziale Italiana (ASI)/Italy.
– British National Space Centre (BNSC)/United Kingdom.
– Canadian Space Agency (CSA)/Canada.
– Centre National d’Etudes Spatiales (CNES)/France.
– Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)/Germany.
– European Space Agency (ESA)/Europe.
– Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.
– Japan Aerospace Exploration Agency (JAXA)/Japan.
– National Aeronautics and Space Administration (NASA)/USA.
– Russian Federal Space Agency (FSA)/Russian Federation.

Observer Agencies
– Austrian Space Agency (ASA)/Austria.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
– Centro Tecnico Aeroespacial (CTA)/Brazil.
– Chinese Academy of Space Technology (CAST)/China.
– Commonwealth Scientific and Industrial Research Organization (CSIRO)/Australia.
– Danish Space Research Institute (DSRI)/Denmark.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
– European Telecommunications Satellite Organization (EUTELSAT)/Europe.
– Federal Service of Scientific, Technical & Cultural Affairs (FSST&CA)/Belgium.
– Hellenic National Space Committee (HNSC)/Greece.
– Indian Space Research Organization (ISRO)/India.
– Institute of Space Research (IKI)/Russian Federation.
– KFKI Research Institute for Particle & Nuclear Physics (KFKI)/Hungary.
– MIKOMTEK: CSIR (CSIR)/Republic of South Africa.
– Korea Aerospace Research Institute (KARI)/Korea.
– Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
– National Oceanic & Atmospheric Administration (NOAA)/USA.
– National Space Program Office (NSPO)/Taipei.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
– Swedish Space Corporation (SSC)/Sweden.
– United States Geological Survey (USGS)/USA.

CCSDS 911.5-B-1 Page iv November 2004
8 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
DOCUMENT CONTROL
Document Title Date Status
CCSDS Space Link Extension— November Blue Book, Issue 1
911.5-B-1 Return Operational Control Fields 2004
Service Specification
CCSDS 911.5-B-1 Page v November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
CONTENTS
Section Page
1 INTRODUCTION. 1-1

1.1 PURPOSE OF THIS RECOMMENDATION. 1-1
1.2 SCOPE.1-1
1.3 APPLICABILITY.1-2
1.4 RATIONALE.1-2
1.5 DOCUMENT STRUCTURE.1-2
1.6 DEFINITIONS, NOMENCLATURE, AND CONVENTIONS . 1-4
1.7 REFERENCES.1-14

2 DESCRIPTION OF THE ROCF SERVICE. 2-1

2.1 OVERVIEW.2-1
2.2 SPACE LINK EXTENSION REFERENCE MODEL. 2-2
2.3 SERVICE MANAGEMENT.2-3
2.4 ARCHITECTURE MODEL—FUNCTIONAL VIEW.2-4
2.5 ARCHITECTURE MODEL—CROSS SUPPORT VIEW . 2-7
2.6 FUNCTIONAL DESCRIPTION.2-8
2.7 OPERATIONAL SCENARIO.2-18
2.8 SECURITY ASPECTS OF THE SLE ROCF TRANSFER SERVICE . 2-19

3 ROCF SERVICE OPERATIONS . 3-1

3.1 GENERAL CONSIDERATIONS.3-1
3.2 ROCF-BIND.3-14
3.3 ROCF-UNBIND.3-20
3.4 ROCF-START.3-24
3.5 ROCF-STOP.3-32
3.6 ROCF-TRANSFER-DATA.3-34
3.7 ROCF-SYNC-NOTIFY.3-37
3.8 ROCF-SCHEDULE-STATUS-REPORT.3-41
3.9 ROCF-STATUS-REPORT.3-45
3.10 ROCF-GET-PARAMETER.3-48
3.11 ROCF-PEER-ABORT.3-52

4 ROCF PROTOCOL . 4-1
CCSDS 911.5-B-1 Page vi November 2004
10 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE

CONTENTS (continued)
Section Page
4.1 GENERIC PROTOCOL CHARACTERISTICS.4-1
4.2 ROCF SERVICE PROVIDER BEHAVIOR. 4-4

ANNEX A Data Type Definitions. A-1
ANNEX B Index to Definitions.B-26
ANNEX C Acronyms. C-1
ANNEX D Conformance Matrix . D-1
ANNEX E Informative References.E-1

Figure
1-1 SLE Services Documentation. 1-4
2-1 Return Frame Processing SLE-FG . 2-4
2-2 ROCF Service Production and Provision. 2-7
2-3 Example of the Management and Provision of ROCF Service. 2-8
2-4 Simplified ROCF Service Provider State Transition Diagram. 2-11
2-5 Communications Realization of ROCF Service. 2-13
2-6 Buffers and Delivery Modes . 2-17

Table
Table 2-1 ROCF Operations . 2-9
Table 3-1 Setting of ROCF Service Configuration Parameters. 3-5
Table 3-2 ROCF-BIND Parameters. 3-15
Table 3-3 ROCF-UNBIND Parameters. 3-21
Table 3-4 ROCF-START Parameters. 3-25
Table 3-5 ROCF-STOP Parameters. 3-32
Table 3-6 ROCF-TRANSFER-DATA Parameters. 3-34
Table 3-7 ROCF-SYNC-NOTIFY Parameters. 3-37
Table 3-8 ROCF-SCHEDULE-STATUS-REPORT Parameters. 3-42
Table 3-9 ROCF-STATUS-REPORT Parameters. 3-45
Table 3-10 ROCF-GET-PARAMETER Parameters . 3-48
Table 3-11 ROCF Parameters. 3-50
Table 3-12 ROCF-PEER-ABORT Parameters. 3-52
Table 4-1 Provider Behavior. 4-6
Table 4-2 Event Description References . 4-13
Table 4-3 Predicate Descriptions. 4-13
Table 4-4 Boolean Flags . 4-14
Table 4-5 Compound Action Definitions . 4-14
CCSDS 911.5-B-1 Page vii November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
CONTENTS (continued)
Table D-1 Conformance Matrix for ROCF Service (Operations) . D-1
Table D-2 Conformance Matrix for ROCF Service (Other Requirements) . D-2

CCSDS 911.5-B-1 Page viii November 2004
12 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
1 INTRODUCTION
1.1 PURPOSE OF THIS RECOMMENDATION
The purpose of this Recommendation is to define the Space Link Extension (SLE) Return
Operational Control Fields (ROCF) service in conformance with the SLE Reference Model
(reference [1]). The ROCF service is an SLE transfer service that delivers to a mission user
all operational control fields from one master channel or one virtual channel.
NOTE – The first issue of reference [1] defines the Return Master Channel Operational
Control Field (Rtn MC-OCF) service and the Return Virtual Channel Operational
Control Field (Rtn VC-OCF) service as two distinct services. Subsequent study
has indicated that it is preferable to define one service that provides the
functionality of both. The ROCF service defined here does just that. It is
anticipated that the next issue of reference [1] will take the same approach,
deleting the Rtn MC-OCF and Rtn VC-OCF services and replacing them with the
Rtn OCF service.
1.2 SCOPE
This Recommendation defines, in an abstract manner, the ROCF service in terms of:
a) the operations necessary to provide the service;
b) the parameter data associated with each operation;
c) the behaviors that result from the invocation of each operation; and
d) the relationship between, and the valid sequence of, the operations and resulting
behaviors.
It does not specify:
a) individual implementations or products;
b) the implementation of entities or interfaces within real systems;
c) the methods or technologies required to acquire telemetry frames from signals
received from a spacecraft;
d) the methods or technologies required to provide a suitable environment for
communications; or
e) the management activities required to schedule, configure, and control the ROCF
service.
CCSDS 911.5-B-1 Page 1-1 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
1.3 APPLICABILITY
1.3.1 APPLICABILITY OF THIS RECOMMENDATION
This Recommendation provides a basis for the development of real systems that implement
the ROCF service. Implementation of the ROCF service in a real system additionally
requires the availability of a communications service to convey invocations and returns of
ROCF service operations between ROCF service users and providers. This
Recommendation requires that such a communications service must ensure that invocations
and returns of operations are transferred:
a) in sequence;
b) completely and with integrity;
c) without duplication;
d) with flow control that notifies the application layer in the event of congestion; and
e) with notification to the application layer in the event that communications between
the ROCF service user and the ROCF service provider are disrupted, possibly
resulting in a loss of data.
It is the specific intent of this Recommendation to define the ROCF service in a manner that
is independent of any particular communications services, protocols, or technologies.
1.3.2 LIMITS OF APPLICABILITY
This Recommendation specifies the ROCF service that may be provided by an SLE Complex
for inter-Agency cross support. It is neither a specification of, nor a design for, real systems
that may be implemented for the control and monitoring of existing or future missions.
1.4 RATIONALE
The goal of this Recommendation is to create a standard for interoperability between the
tracking stations or ground data handling systems of various Agencies and the consumers of
spacecraft telemetry.
1.5 DOCUMENT STRUCTURE
1.5.1 ORGANIZATION
This document is organized as follows:
a) section 1 presents the purpose, scope, applicability and rationale of this
Recommendation and lists the definitions, conventions, and references used
throughout the Recommendation;
CCSDS 911.5-B-1 Page 1-2 November 2004
14 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
b) section 2 provides an overview of the ROCF service including a functional
description, the service management context, and protocol considerations;
c) section 3 specifies the operations of the ROCF service;
d) section 4 specifies the dynamic behavior of the ROCF service in terms of the state
transitions of the ROCF service provider;
e) annex A provides a formal specification of ROCF service data types using Abstract
Syntax Notation One (ASN.1);
f) annex B lists all terms used in this Recommendation and identifies where they are
defined;
g) annex C lists all acronyms used within this document;
h) annex D provides a conformance matrix that defines what capabilities must be
provided for an implementation to be considered compliant with this
Recommendation;
i) annex E provides a list of informative references.
1.5.2 SLE SERVICES DOCUMENTATION TREE
This Recommendation is based on the cross support model defined in the SLE Reference
Model (reference [1]). It expands upon the concept of an SLE transfer service as an
interaction between an SLE Mission User Entity (MUE) and an SLE transfer service
provider for the purpose of providing the ROCF transfer service.
This Recommendation is part of a suite of documents specifying the SLE services. The SLE
services constitute one of the three types of Cross Support Services:
a) Part 1: SLE Services;
b) Part 2: Ground Domain Services;
c) Part 3: Ground Communications Services.
The basic organization of the SLE services documentation is shown in figure 1-1. The
various documents are described in the following paragraphs.
CCSDS 911.5-B-1 Page 1-3 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
SpSpacacee L Liinnkk Ex Extteennssiioonn
CCrroossss S Suupppportort
CrCrossoss S Supuppoporrtt CoConcepncept t  SSLLE EE Exxecutiecutivvee
RefeReferere ncnce Me Moodedell
Part 1: Part 1: S SLLE E SSeervrviicceses SuSummmmaryary

PaParrtt 1 1:: SL SLE SeE Serrvviicceess
SSSLELLEE T T Trrrananansfsfsfererer S S Seeervrvrviceiceicesss
FFFooorrrwwwaaarrrddd SL SL SLE SeE SeE Serrrvvviiiccceee      SLSLSLE APE APE APIII f f fooorrr
RRReeetttuuurrrnnn SL SL SLE SeE SeE Serrrvvviiiccceee   SLSLSLE SeE SeE Serrrvvviiiccceee
SSSpppecieciecifffiiicccaaatttiiionsonsons     TranTranTransssfffeeer Sr Sr Seeervrvrviiiccceseses
SSSpppeeecccififificicicaaatttiiiooonsnsns  MMMaaanananagegegemmmeeentntnt S S Suiuiuitetete
RRRecoecoecommmmmmeeendandandatttiiiononon     RRReport (eport (eport (GGGreereereennn)))  RRRepoepoeport (rt (rt (YYYeeellowllowllow)))
LLLegenegenegend:d:d:
Figure 1-1: SLE Services Documentation
a) Cross Support Concept—Part 1: Space Link Extension Services (reference [E2]): a
Report introducing the concepts of cross support and the SLE services;
b) Cross Support Reference Model—Part 1: Space Link Extension Services (reference
[1]): a Recommendation that defines the framework and terminology for the
specification of SLE services;
c) SLE Return Service Specifications: a set of Recommendations that will provide
specification of all return link SLE services (this Recommendation is one of the
specifications in that set);
d) SLE Forward Service Specifications: a set of Recommendations that will provide
specification of all forward link SLE services;
e) SLE Service Management Specifications: a set of Recommendations that establish
the basis of SLE service management.
1.6 DEFINITIONS, NOMENCLATURE, AND CONVENTIONS
1.6.1 DEFINITIONS
1.6.1.1 Definitions from Open Systems Interconnection (OSI) Basic Reference Model
This Recommendation makes use of a number of terms defined in reference [8]. The use of
those terms in this Recommendation shall be understood in a generic sense; i.e., in the sense
CCSDS 911.5-B-1 Page 1-4 November 2004
16 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
that those terms are generally applicable to technologies that provide for the exchange of
information between real systems. Those terms are:
a) abstract syntax;
b) application entity;
c) application layer;
d) application process;
e) flow control;
f) Open Systems Interconnection (OSI);
g) real system;
h) Service Access Point (SAP).
1.6.1.2 Definitions from Abstract Syntax Notation One
This Recommendation makes use of the following terms defined in reference [9]:
a) Abstract Syntax Notation One (ASN.1);
b) object identifier;
c) (data) type;
d) (data) value.
NOTE – In annex A of this Recommendation, ASN.1 is used for specifying the abstract
syntax of ROCF service operation invocations and returns. The use of ASN.1 as
a descriptive language is intended to support the specification of the abstract
ROCF service; it is not intended to constrain implementations. In particular,
there is no requirement for implementations to employ ASN.1 encoding rules.
ASN.1 is simply a convenient tool for formally describing the abstract syntax of
ROCF service operation invocations and returns.
1.6.1.3 Definitions from TM Synchronization and Channel Coding
This Recommendation makes use of the following terms defined in reference [2]:
a) Attached Sync Marker;
b) Reed-Solomon check symbols;
c) Reed-Solomon code.
CCSDS 911.5-B-1 Page 1-5 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
1.6.1.4 Definitions from TM Space Data Link Protocol
This Recommendation makes use of the following term defined in reference [3]:
a) Frame Error Control Field (FECF);
b) (Virtual Channel or Master Channel) Operational Control Field (OCF);
c) TM Transfer Frame.
1.6.1.5 Definitions from TC Space Data Link Protocol
This Recommendation makes use of the following terms defined in reference [4]:
a) Communications Link Control Word (CLCW);
b) Control Word Type.
1.6.1.6 Definitions from AOS Space Data Link Protocol
This Recommendation makes use of the following terms defined in reference [5]:
a) AOS Transfer Frame;
b) Frame Error Control Field (FECF);
c) (Virtual Channel or Master Channel) Operational Control Field (OCF).
1.6.1.7 Definitions from SLE Reference Model
This Recommendation makes use of the following terms defined in reference [1]:
a) abstract binding;
b) abstract object;
c) abstract port;
d) abstract service;
e) invoker;
f) Master Channel Operational Control Field SLE data channel (MCOCF channel)
g) Mission Data Operation System (MDOS);
h) Mission User Entity (MUE);
i) offline delivery mode;
j) online delivery mode;
CCSDS 911.5-B-1 Page 1-6 November 2004
18 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
k) operation;
l) performer;
m) physical channel;
n) return data;
o) Return All Frames channel (RAF channel);
p) Return All Frames service (RAF service);
q) Return Master Channel Operational Control Field service (MCOCF service);
r) Return Virtual Channel Operational Control Field service (VCOCF service);
s) service agreement;
t) service provider (provider);
u) service user (user);
v) SLE Complex;
w) SLE Complex Management;
x) SLE data channel;
y) SLE Functional Group (SLE-FG);
z) SLE Protocol Data Unit (SLE-PDU);
aa) SLE Service Data Unit (SLE-SDU);
bb) SLE service package;
cc) SLE System;
dd) SLE transfer service instance;
ee) SLE transfer service production;
ff) SLE transfer service provision;
gg) SLE Utilization Management;
hh) space link;
ii) space link data channel;
jj) Space Link Data Unit (SL-DU);
kk) space link session;
ll) Virtual Channel Operational Control Field SLE data channel (VCOCF channel).
CCSDS 911.5-B-1 Page 1-7 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
1.6.1.8 Additional Definitions
1.6.1.8.1 Association
An association is a cooperative relationship between an SLE service-providing application
entity and an SLE service-using application entity. An association is formed by the
exchange of SLE protocol data units through the use of an underlying communications
service.
1.6.1.8.2 Communications Service
A communications service is a capability that enables an SLE service-providing application
entity and an SLE service-using application entity to exchange information.
NOTE – If an SLE service user and an SLE service provider are implemented using
different communications services, then interoperability between them is possible
only by means of a suitable gateway. Adherence to this Recommendation
ensures, at least in principle, that it is possible to construct such a gateway.
1.6.1.8.3 Confirmed Operation
A confirmed operation is an operation that requires the performer to return a report of its
outcome to the invoker.
1.6.1.8.4 Delivery Criteria
Delivery criteria are rules that determine whether a data unit acquired from the space link by
an SLE service provider shall be delivered to a user.
NOTE – For ROCF service, the delivery criteria are:
a) the Earth Receive Time (ERT) of the frame from which the OCF is extracted
is within the period defined by the start and stop times specified in the
ROCF-START operation;
b) the spacecraft identifier (SCID) of the frame matches the SCID of the global
VCID specified in the ROCF-START operation;
c) the virtual channel identifier (VCID) of the frame matches the VCID of the
global VCID specified in the ROCF-START operation;
d) the type of the control word contained in the extracted OCF matches the type
specified in the ROCF-START operation;
e) for CLCW reports, i.e., for OCFs containing a control word of type ‘0’
(reference [4]), the telecommand virtual channel that the report refers to
CCSDS 911.5-B-1 Page 1-8 November 2004
20 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
matches the telecommand virtual channel specified in the ROCF-START
operation.
1.6.1.8.5 Frame Error Control Field
The Frame Error Control Field (FECF) of a frame is the FECF of a TM Transfer Frame
(reference [3]) or the FECF of an AOS Transfer Frame (reference [5]), as applicable.
1.6.1.8.6 Initiator
The initiator is the object that issues the request to bind to another object (the responder).
1.6.1.8.7 Invocation
The invocation of an operation is the making of a request by an object (the invoker) to
another object (the performer) to carry out the operation.
1.6.1.8.8 Master Channel
The sequence of all telemetry frames with the same Transfer Frame Version Number
(TFVN) and the same SCID on the same physical channel constitutes a master channel.
NOTE – Depending on the TFVN, the definition of SCID is as given in either reference
[3] or reference [5].
1.6.1.8.9 Operational Control Field
The Operational Control Field (OCF) of a telemetry frame is the frame OCF of either a TM
Transfer Frame (reference [3]) or an AOS Transfer Frame (reference [5]).
1.6.1.8.10 Parameter
A parameter of an operation is data that may accompany the operation’s invocation or return.
NOTE – The term parameter is also used to refer to mission-dependent configuration
information used in the production or provision of the service.
1.6.1.8.11 Performance
The performance of an operation is the carrying out of the operation by an object (the
performer).
CCSDS 911.5-B-1 Page 1-9 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
1.6.1.8.12 Port Identifier
A port identifier identifies a source or a destination in a communications system.
NOTE – See 2.6.4.5 for more information.
1.6.1.8.13 Responder
The responder is the object that receives a request to bind and completes the binding (if
possible) with the initiator in order for a service association to exist between the two objects.
1.6.1.8.14 Return
The return of an operation is a report, from the performer to the invoker, of the outcome of
the performance of the operation.
1.6.1.8.15 Service Instance Provision Period
A service instance provision period is the time during which a service instance (i.e., the
capability to transfer one or more SLE data channels of a given type) is scheduled to be
provided.
NOTE – Reaching of the beginning of this period constitutes the event ‘start of service
instance provision period’ (see 4.2.2).
1.6.1.8.16 Spacecraft Identifier
The spacecraft identifier (SCID) of a telemetry frame is as defined in reference [3] if the
frame is a TM Transfer Frame or as defined in reference [5] if the frame is an AOS Transfer
Frame.
1.6.1.8.17 Telemetry Frame
A (telemetry) frame is a TM Transfer Frame (as defined in reference [3]) or an AOS Transfer
Frame (as defined in reference [5]). In case a distinction of the frame versions is necessary,
the full term as per references [3] or [5] is used.
1.6.1.8.18 Transfer Frame Version Number
The Transfer Frame Version Number (TFVN) is either the TFVN as defined in reference [3]
or the TFVN as defined in reference [5].
CCSDS 911.5-B-1 Page 1-10 November 2004
22 © ISO 2007 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
NOTE – The definitions of TFVN given in references [3] and [5] are equivalent. If a
CCSDS-compatible telemetry frame is known to contain no errors, the TFVN
enables one to distinguish between a TM Transfer Frame and an AOS Transfer
Frame.
1.6.1.8.19 Unconfirmed Operation
An unconfirmed operation is an operation that does not require a report of its outcome to be
returned to the invoker by the performer.
1.6.1.8.20 Virtual Channel
All telemetry frames with the same TFVN, the same SCID, and the same virtual channel
identifier (VCID) on the same physical channel constitute a virtual channel.
1.6.1.8.21 Virtual Channel Identifier
The virtual channel identifier (VCID) of a telemetry frame is as defined in reference [3] if the
telemetry frame is a TM transfer frame or as defined in reference [5] if the telemetry frame is
an AOS Transfer Frame.
1.6.2 NOMENCLATURE
The following conventions apply throughout this Recommendation:
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.
1.6.3 CONVENTIONS
1.6.3.1 Specification of Operations
1.6.3.1.1 General
Section 3 of this Recommendation specifies the operations that constitute the ROCF service.
The specification of each operation is divided into subsections as described in 1.6.3.1.2
through 1.6.3.1.4.
CCSDS 911.5-B-1 Page 1-11 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN OCF SERVICE
1.6.3.1.2 Purpose Subsection
The Purpose subsection provides a brief description of the purpose of the operation.
Additionally, it indicates whether the operation may be invoked by the user, provider, or
both; whether the operation is confirmed or unconfirmed; and whether there are any
constraints on when the operation may be invoked.
1.6.3.1.3 Invocation, Return, and Parameters Subsection
The Invocation, Return, and Parameters subsection describes the parameters associated with
each operation, including their semantics. A table accompanying the description of each
operation lists all parameters associated with the operation and, for both the invocation and
return, whether the parameter is always present, always absent, or conditionally present.
For parameters that are conditionally present, the parameter description specifies the
conditions for the presence or absence of the parameter. The condition is generally based on
the value of another parameter in the same invocation or return; for example, in the return of
an operation, the diagnostic parameter is present if and only if the value of the result
parameter is ‘negative result’. For a conditional parameter in a return, the condition may be
based on the value of a parameter in the corresponding invocation.
In the table, the following convention is used to indicate whether a parameter is always
present, always absent, or conditionally present:
M Always present
C Conditionally present
Blank Always absent
NOTE – Even though a parameter may be characterized as always present, its description
may specify that its value is permitted to be ‘null’ or ‘unused’ or the like.
1.6.3.1.4 Effects Subsection
The Effects subsection describes the effects an operation has on the invoker, the performer,
the association between them, or any combination thereof. The details of how those effects
occur or the mechanisms used are outsi
...