ISO 26143:2021

INTERNATIONAL ISO
STANDARD 26143
Third edition
2021-06
Space data and information transfer
systems — Space link extension (SLE)
— Return operational control fields
service specification
Systèmes de transfert des données et informations spatiales —
Extension de liaisons spatiales (SLE) — Service des champs de
contrôle de retour opérationnel
Reference number
ISO 26143:2021(E)
©
ISO 2021

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ISO 26143:2021(E)

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ISO 26143:2021(E)
Foreword
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different types of ISO documents should be noted (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
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the ISO list of patent declarations received (see www.iso.org/patents).
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www.iso.org/iso/foreword.html.
This document was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as CCSDS
911.5-B-3, August 2016) and was adopted (without modifications) by Technical Committee ISO/TC 20,
Space vehicles, Subcommittee SC 13, Space data and information transfer systems.
This third edition cancels and replaces the second edition (ISO 26143:2013), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— adds clarifications and corrections;
— adds production status annex.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
CONTENTS
Section Page
1 INTRODUCTION . 1-1
1.1 PURPOSE OF THIS RECOMMENDED STANDARD . 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 . 1-5
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 . 3-15
3.3 ROCF-UNBIND . 3-22
3.4 ROCF-START . 3-26
3.5 ROCF-STOP . 3-34
3.6 ROCF-TRANSFER-DATA . 3-36
3.7 ROCF-SYNC-NOTIFY . 3-40
3.8 ROCF-SCHEDULE-STATUS-REPORT . 3-44
3.9 ROCF-STATUS-REPORT . 3-48
3.10 ROCF-GET-PARAMETER . 3-51
3.11 ROCF-PEER-ABORT . 3-56
4 ROCF PROTOCOL . 4-1
4.1 GENERIC PROTOCOL CHARACTERISTICS . 4-1
4.2 ROCF SERVICE PROVIDER BEHAVIOR . 4-4
CCSDS 911.5-B-3 Page vi August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
CONTENTS (continued)
Section Page

ANNEX A DATA TYPE DEFINITIONS (NORMATIVE) . A-1
ANNEX B PRODUCTION STATUS (NORMATIVE) .B-1
ANNEX C CONFORMANCE MATRIX (NORMATIVE) . C-1
ANNEX D INDEX TO DEFINITIONS (INFORMATIVE) . D-1
ANNEX E ACRONYMS (INFORMATIVE) .E-1
ANNEX F INFORMATIVE REFERENCES (INFORMATIVE) . F-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 . 2-18
B-1 ROCF Production Status Transitions .B-1

Table
2-1 ROCF Operations . 2-9
3-1 Setting of ROCF Service Configuration Parameters . 3-6
3-2 ROCF-BIND Parameters . 3-16
3-3 ROCF-UNBIND Parameters . 3-23
3-4 ROCF-START Parameters . 3-27
3-5 ROCF-STOP Parameters . 3-34
3-6 ROCF-TRANSFER-DATA Parameters . 3-36
3-7 ROCF-SYNC-NOTIFY Parameters . 3-40
3-8 ROCF-SCHEDULE-STATUS-REPORT Parameters . 3-45
3-9 ROCF-STATUS-REPORT Parameters . 3-48
3-10 ROCF-GET-PARAMETER Parameters . 3-51
3-11 ROCF Parameters . 3-53
3-12 ROCF-PEER-ABORT Parameters . 3-56
4-1 Provider Behavior . 4-6
4-2 Event Description References . 4-12
4-3 Predicate Descriptions . 4-12
4-4 Boolean Flags . 4-13
4-5 Compound Action Definitions . 4-13
B-1 Production Status Changes and Notifications .B-2
B-2 Effect of Production Status on Operations .B-3
C-1 Conformance Matrix for ROCF Service (Operations) .C-1
C-2 Conformance Matrix for ROCF Service (Other Requirements) .C-2
CCSDS 911.5-B-3 Page vii August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
1 INTRODUCTION
1.1 PURPOSE OF THIS RECOMMENDED STANDARD
The purpose of this Recommended Standard 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 – 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 a future 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 Recommended Standard 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-3 Page 1-1 August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
1.3 APPLICABILITY
1.3.1 APPLICABILITY OF THIS RECOMMENDED STANDARD
This Recommended Standard 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
Recommended Standard 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 Recommended Standard 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 Recommended Standard 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 Recommended Standard 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:
CCSDS 911.5-B-3 Page 1-2 August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
a) section 1 presents the purpose, scope, applicability and rationale of this
Recommended Standard and lists the definitions, conventions, and references used
throughout the Recommended Standard;
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 specifies the relationship of the ROCF service provision to the production
status;
g) annex C provides a conformance matrix that defines what capabilities must be
provided for an implementation to be considered compliant with this Recommended
Standard;
h) annex D lists all terms used in this Recommended Standard and identifies where they
are defined;
i) annex E lists all acronyms used within this document;
j) annex F provides a list of informative references.
1.5.2 SLE SERVICES DOCUMENTATION TREE
This Recommended Standard 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 Recommended Standard 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-3 Page 1-3 August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
Space Link Extension
Cross Support
Cross Support Concept SLE Executive
Reference Model
Part 1: SLE Services Summary
Part 1: SLE Services
SLE Transfer Services
Forward SLE Service
Return SLE Service
Specifications Specifications
SLE Service
Management Suite
SLE API for Internet Protocol for
Transfer Services Transfer Services
Recommended Recommended Informational
Legend:
Record (Yellow)
Standard (Blue) Practice (Magenta) Report (Green)

Figure 1-1: SLE Services Documentation
a) Cross Support Concept—Part 1: Space Link Extension Services (reference [F2]): 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 Recommended Standard that defines the framework and
terminology for the specification of SLE services;
c) SLE Return Service Specifications: a set of Recommended Standards that will
provide specification of all return link SLE services (this Recommended Standard is
one of the specifications in that set);
d) SLE Forward Service Specifications: a set of Recommended Standards that will
provide specification of all forward link SLE services;
e) SLE API for Transfer Services Specifications: a set of Recommended Practices that
provide specifications of an Application Program Interface; a set of Recommended
Standards that provide specifications of an Application Program Interface and a
mapping to TCP/IP as underlying communications service for SLE services;
f) Internet Protocol for Transfer Services: defines a protocol for transfer of SLE
Protocol Data Units using TCP/IP as underlying communications service for SLE
services;
g) SLE Service Management Specifications: a set of Recommended Standards that
establish the basis of SLE service management.
CCSDS 911.5-B-3 Page 1-4 August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
1.6 DEFINITIONS, NOMENCLATURE, AND CONVENTIONS
1.6.1 DEFINITIONS
1.6.1.1 Definitions from Open Systems Interconnection (OSI) Basic Reference Model
This Recommended Standard makes use of a number of terms defined in reference [8]. The
use of those terms in this Recommended Standard shall be understood in a generic sense, i.e.,
in the sense 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 Recommended Standard 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 Recommended Standard, 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 Recommended Standard makes use of the following terms defined in reference [2]:
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
a) Attached Sync Marker;
b) Reed-Solomon check symbols;
c) Reed-Solomon code.
1.6.1.4 Definitions from TM Space Data Link Protocol
This Recommended Standard 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 Recommended Standard 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 Recommended Standard makes use of the following terms defined in reference [6]:
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 Recommended Standard 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)
CCSDS 911.5-B-3 Page 1-6 August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
g) Mission Data Operation System (MDOS);
h) Mission User Entity (MUE);
i) offline delivery mode;
j) online delivery mode;
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 transfer service instance;
dd) SLE transfer service production;
ee) SLE transfer service provision;
ff) SLE Utilization Management;
gg) space link;
hh) space link data channel;
CCSDS 911.5-B-3 Page 1-7 August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
ii) Space Link Data Unit (SL-DU);
jj) space link session;
kk) Virtual Channel Operational Control Field SLE data channel (VCOCF channel).
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 Recommended Standard
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;
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
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
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 [6]), as applicable.
1.6.1.8.6 Initiator
The initiator is the object that issues the request to bind to another object (the responder).
NOTE – In other words, the initiator is always the invoker of the request to bind to
another object. Therefore, in the context of the request to bind, the terms
‘initiator’ and ‘invoker’ refer to the same object and are synonyms.
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 [6].
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 [6]).
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
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).
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.
NOTE – In other words, the responder is always the performer of the binding. Therefore,
in the context of binding, the terms ‘responder’ and ‘performer’ refer to the same
object and are synonyms.
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).
CCSDS 911.5-B-3 Page 1-10 August 2016
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ISO 26143:2021(E)
CCSDS RECOMMENDED STANDARD FOR SLE ROCF SERVICE
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 [6] if the frame is an AOS Transfer
Frame.
1.6.1.8.17 Telemetry Frame
A (telemetry) frame is a TM Tran
...