IEC 61158-4-12:2010

IEC 61158-4-12 ®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 4-12: Data-link layer protocol specification – Type 12 elements

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IEC 61158-4-12 ®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 4-12: Data-link layer protocol specification – Type 12 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XG
ICS 25.04.40; 35.100.20; 35.110 ISBN 978-2-88912-087-1
– 2 – 61158-4-12 © IEC:2010(E)
CONTENTS
FOREWORD.7
INTRODUCTION.9
1 Scope.10
1.1 General .10
1.2 Specifications.10
1.3 Procedures.10
1.4 Applicability.10
1.5 Conformance.10
2 Normative references .11
3 Terms, definitions, symbols and abbreviations.11
3.1 Reference model terms and definitions.11
3.2 Service convention terms and definitions.12
3.3 Common terms and definitions .13
3.4 Additional Type 12 definitions.13
3.5 Common symbols and abbreviations .16
3.6 Additional Type 12 symbols and abbreviations .17
3.7 Conventions .18
4 Overview of the DL-protocol .23
4.1 Operating principle .23
4.2 Topology .23
4.3 Frame processing principles.23
4.4 Data-link layer overview .24
4.5 Error detection overview.25
4.6 Node reference model .25
4.7 Operation overview .26
5 Frame structure .27
5.1 Frame coding principles .27
5.2 Data types and encoding rules .27
5.3 DLPDU structure .29
5.4 Type 12 DLPDU structure.32
5.5 Network variable structure.48
5.6 Type 12 mailbox structure .48
6 Attributes.50
6.1 Management .50
6.2 Statistics .66
6.3 Watchdogs .69
6.4 Slave information interface .72
6.5 Media independent interface (MII) .77
6.6 Fieldbus memory management unit (FMMU).80
6.7 Sync manager .83
6.8 Distributed clock.89
7 DL-user memory.93
7.1 Overview .93
7.2 Mailbox access type .94
7.3 Buffered access type.97

61158-4-12 © IEC:2010(E) – 3 –
8 Type 12: FDL protocol state machines.99
8.1 Overview of slave DL state machines .99
8.2 State machine description .99
Annex A (informative)  Type 12: Additional specifications on DL-Protocol state
machines .107
Bibliography.141

Figure 1 – Type description example .19
Figure 2 – Common structure of specific fields.20
Figure 3 – Frame structure.24
Figure 4 – Mapping of data in a frame.25
Figure 5 – Slave node reference model.26
Figure 6 – Type 12 PDUs embedded in Ethernet frame.27
Figure 7 – Type 12 PDUs embedded in UDP/IP .27
Figure 8 – DL information type description .51
Figure 9 – Address type description.53
Figure 10 – DL control type description.55
Figure 11 – DL status type description .57
Figure 12 – Successful write sequence to DL-user control register .59
Figure 13 – Successful read sequence to the DL-user status register .60
Figure 14 – RX error counter type description .67
Figure 15 – Lost link counter type description .68
Figure 16 – Additional counter type description.69
Figure 17 – Sync configuration type description .70
Figure 18 – Watchdog divider type description.70
Figure 19 – Sync manager watchdog type description.71
Figure 20 – Sync manager watchdog status type description .71
Figure 21 – Watchdog counter type description.72
Figure 22 – Slave information interface access type description .72
Figure 23 – Slave information interface control/status type description .74
Figure 24 – Slave information interface address type description.76
Figure 25 – Slave information interface data type description .77
Figure 26 – MII control/status type description .78
Figure 27 – MII address type description .79
Figure 28 – MII data type description .80
Figure 29 – FMMU mapping example.80
Figure 30 – FMMU entity type description .81
Figure 31 – SyncM mailbox interaction.84
Figure 32 – SyncM buffer allocation.84
Figure 33 – SyncM buffer interaction .85
Figure 34 – Handling of write/read toggle with read mailbox .85
Figure 35 – Sync manager channel type description .87
Figure 36 – Distributed clock local time parameter type description .91
Figure 37 – Successful write sequence to mailbox .94

– 4 – 61158-4-12 © IEC:2010(E)
Figure 38 – Bad write sequence to mailbox.95
Figure 39 – Successful read sequence to mailbox.95
Figure 40 – Bad read sequence to mailbox .96
Figure 41 – Successful write sequence to buffer .97
Figure 42 – Successful read sequence to buffer.98
Figure 43 – Structuring of the protocol machines of an slave .99
Figure 44 – Slave information interface read operation . 101
Figure 45 – Slave information interface write operation. 102
Figure 46 – Slave information interface reload operation . 103
Figure 47 – Distributed clock .105
Figure 48 – Delay measurement sequence . 106

Table 1 – PDU element description example.19
Table 2 – Example attribute description .20
Table 3 – State machine description elements .21
Table 4 – Description of state machine elements .22
Table 5 – Conventions used in state machines .22
Table 6 – Transfer Syntax for bit sequences .28
Table 7 – Transfer syntax for data type Unsignedn .28
Table 8 – Transfer syntax for data type Integern .29
Table 9 – Type 12 frame inside an Ethernet frame.30
Table 10 – Type 12 frame inside an UDP PDU.30
Table 11 – Type 12 frame structure containing Type 12 PDUs .31
Table 12 – Type 12 frame structure containing network variables .31
Table 13 – Type 12 frame structure containing mailbox .32
Table 14 – Auto increment physical read (APRD).32
Table 15 – Configured address physical read (FPRD).33
Table 16 – Broadcast read (BRD) .34
Table 17 – Logical read (LRD) .35
Table 18 – Auto Increment physical write (APWR) .37
Table 19 – Configured address physical write (FPWR).38
Table 20 – Broadcast write (BWR) .39
Table 21 – Logical write (LWR) .40
Table 22 – Auto increment physical read write (APRW) .41
Table 23 – Configured address physical read write (FPRW).42
Table 24 – Broadcast read write (BRW) .43
Table 25 – Logical read write (LRW) .44
Table 26 – Auto increment physical read multiple write (ARMW).46
Table 27 – Configured address physical read multiple write (FRMW) .47
Table 28 – Network variable .48
Table 29 – Mailbox .49
Table 30 – Error Reply Service Data.49
Table 31 – DL information.52

61158-4-12 © IEC:2010(E) – 5 –
Table 32 – Configured station address.54
Table 33 – DL control .55
Table 34 – DL status.58
Table 35 – DLS-user specific registers.60
Table 36 – DLS-user event .62
Table 37 – DLS-user event mask .64
Table 38 – External event .65
Table 39 – External event mask.66
Table 40 – RX error counter.67
Table 41 – Lost link counter.68
Table 42 – Additional counter .69
Table 43 – Watchdog divider.70
Table 44 – DLS-user watchdog .70
Table 45 – Sync manager channel watchdog .71
Table 46 – Sync manager watchdog Status .71
Table 47 – Watchdog counter .72
Table 48 – Slave information interface access .72
Table 49 – Slave information interface control/status .75
Table 50 – Actual slave information interface address .76
Table 51 – Actual slave information interface data .77
Table 52 – MII control/status.78
Table 53 – Actual MII address.79
Table 54 – Actual MII data .80
Table 55 – Fieldbus memory management unit (FMMU) entity .82
Table 56 – Fieldbus memory management unit (FMMU).83
Table 57 – Sync manager channel .87
Table 58 – Sync manager Structure .89
Table 59 – Distributed clock local time parameter .92
Table 60 – Distributed clock DLS-user parameter .93
Table A.1 – Primitives issued by DHSM to PSM.107
Table A.2 – Primitives issued by PSM to DHSM.107
Table A.3 – Parameters used with primitives exchanged between DHSM and PSM. 107
Table A.4 – Identifier for the octets of a Ethernet frame .108
Table A.5 – DHSM state table.110
Table A.6 – DHSM function table .125
Table A.7 – Primitives issued by SYSM to DHSM.125
Table A.8 – Primitives issued by DHSM to SYSM.126
Table A.9 – Primitives issued by DL-User to SYSM.126
Table A.10 – Primitives issued by SYSM to DL-User.126
Table A.11 – Parameters used with primitives exchanged between SYSM and DHSM . 126
Table A.12 – SYSM state table .128
Table A.13 – SYSM function table.137
Table A.14 – Primitives issued by RMSM to SYSM .137

– 6 – 61158-4-12 © IEC:2010(E)
Table A.15 – Primitives issued by SYSM to RMSM .138
Table A.16 – Parameters used with primitives exchanged between RMSM and SYSM . 138
Table A.17 – RMSM state table.139
Table A.18 – RMSM function table.140

61158-4-12 © IEC:2010(E) – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 4-12: Data-link layer protocol specification –
Type 12 elements
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
International Standard IEC 61158-4-12 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This second edition cancels and replaces the first edition published in 2007. This edition
constitutes a technical revision.
The main changes with respect to the previous edition are listed below:
• bug fixes and
• editorial improvements.
– 8 – 61158-4-12 © IEC:2010(E)
The text of this standard is based on the following documents:
FDIS Report on voting
65C/605/FDIS 65C/619/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with ISO/IEC Directives, Part 2.
A list of all the parts of the IEC 61158 series, published under the general title Industrial
communication networks – Fieldbus specifications, can be found on the IEC web site.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
NOTE The revision of this standard will be synchronized with the other parts of the IEC 61158 series.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
61158-4-12 © IEC:2010(E) – 9 –
INTRODUCTION
This part of IEC 61158 is one of a series produced to facilitate the interconnection of
automation system components. It is related to other standards in the set as defined by the
“three-layer” fieldbus reference model described in IEC/TR 61158-1.
The data-link protocol provides the data-link service by making use of the services available
from the physical layer. The primary aim of this standard is to provide a set of rules for
communication expressed in terms of the procedures to be carried out by peer data-link
entities (DLEs) at the time of communication. These rules for communication are intended to
provide a sound basis for development in order to serve a variety of purposes:
a) as a guide for implementors and designers;
b) for use in the testing and procurement of equipment;
c) as part of an agreement for the admittance of systems into the open systems environment;
d) as a refinement to the understanding of time-critical communications within OSI.
This standard is concerned, in particular, with the communication and interworking of sensors,
effectors and other automation devices. By using this standard together with other standards
positioned within the OSI or fieldbus reference models, otherwise incompatible systems may
work together in any combination.
NOTE Use of some of the associated protocol types is restricted by their intellectual-property-right holders. In all
cases, the commitment to limited release of intellectual-property-rights made by the holders of those rights permits
a particular data-link layer protocol type to be used with physical layer and application layer protocols in Type
combinations as specified explicitly in the profile parts. Use of the various protocol types in other combinations
may require permission from their respective intellectual-property-right holders.
The International Electrotechnical Commission (IEC) draws attention to the fact that it is
claimed that compliance with this document may involve the use of patents concerning
Type 12 elements and possibly other types given as follows:
EP 1 590 927 B1 [BE] Koppler für ein Netzwerk mit Ringtopologie und ein auf Ethernet basierten Netzwerk
EP 1 789 857 B1 [BE] Datenübertragungsverfahren und automatisierungssystem zum Einsatz eines
solchen Datenübertragungsverfahrens
DE 102007017835.4 [BE] Paketvermittlungsvorrichtung und lokales Kommunikationsnetz mit einer solchen
Paketvermittlungsvorrichtung
EP 1 456 722 B1 [BE] Datenübertragungsverfahren, serielles Bussystem und Anschalteinheit für einen
passiven Busteilnehmer
IEC takes no position concerning the evidence, validity and scope of these patent rights.
The holder of these patent rights has assured the IEC that he/she is willing to negotiate
licences either free of charge or under reasonable and non-discriminatory terms and
conditions with applicants throughout the world. In this respect, the statement of the holder of
these patent rights is registered with IEC. Information may be obtained from:
[BE]: Beckhoff Automation GmbH
Eiserstraße 5
33415 Verl,
Germany
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights other than those identified above. IEC shall not be held responsible for
identifying any or all such patent rights.
ISO (www.iso.org/patents) and IEC (http://www.iec.ch/tctools/patent_decl.htm) maintain on-
line data bases of patents relevant to their standards. Users are encouraged to consult the
data bases for the most up to date information concerning patents.

– 10 – 61158-4-12 © IEC:2010(E)
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 4-12: Data-link layer protocol specification –
Type 12 elements
1 Scope
1.1 General
The data-link layer provides basic time-critical messaging communications between devices in
an automation environment.
This protocol provides communication opportunities to all participating data-link entities
a) in a synchronously-starting cyclic manner, and
b) in a cyclic or acyclic asynchronous manner, as requested each cycle by each of those
data-link entities.
Thus this protocol can be characterized as one which provides cyclic and acyclic access
asynchronously but with a synchronous restart of each cycle.
1.2 Specifications
This standard specifies
a) procedures for the transfer of data and control information from one data-link user entity to
one or more user entity;
b) the structure of the DLPDUs used for the transfer of data and control information by the
protocol of this standard, and their representation as physical interface data units.
1.3 Procedures
The procedures are defined in terms of
a) the interactions between DL-entities (DLEs) through the exchange of DLPDUs;
b) the interactions between a DL-service (DLS) provider and a DLS-user in the same system
through the exchange of DLS primitives;
c) the interactions between a DLS-provider and the MAC services of ISO/IEC 8802-3.
1.4 Applicability
These procedures are applicable to instances of communication between systems which
support time-critical communications services within the data-link layer of the OSI reference
model, and which require the ability to interconnect in an open systems interconnection
environment.
Profiles provide a simple multi-attribute means of summarizing an implementation’s
capabilities, and thus its applicability to various time-critical communications needs.
1.5 Conformance
This standard also specifies conformance requirements for systems implementing these
procedures. This part of this standard does not contain tests to demonstrate compliance with
such requirements.
61158-4-12 © IEC:2010(E) – 11 –
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 61158-2:2010 , Industrial communication networks – Fieldbus specifications – Part 2:
Physical layer specification and service definition
IEC 61158-3-12, Industrial communication networks – Fieldbus specifications – Part 3-12:
Data-link layer service definition – Type 12 elements
IEC 61588, Precision clock synchronization protocol for networked measurement and control
system
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model: The Basic Model
ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model: Naming and addressing
ISO/IEC 8802-3:2000, Information technology – Telecommunications and information
exchange between systems – Local and metropolitan area networks – Specific requirements –
Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and
physical layer specifications
ISO/IEC 9899, Programming Languages – C
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
and metropolitan Area Networks – Virtual Bridged
IEEE 802.1Q, IEEE Standard for Local
Local Area Networks, available at
IETF RFC 768, User Datagram Protocol (UDP), available at
IETF RFC 791, Internet protocol DARPA internet program protocol specification, available at

3 Terms, definitions, symbols and abbreviations
For the purposes of this document, the following terms, definitions, symbols and abbreviations
apply.
3.1 Reference model terms and definitions
This standard is based in part on the concepts developed in ISO/IEC 7498-1 and ISO/IEC
7498-3, and makes use of the following terms defined therein.
3.1.1 DL-duplex-transmission [ISO/IEC 7498-1]
3.1.2 DL-protocol [ISO/IEC 7498-1]
___________
To be published
– 12 – 61158-4-12 © IEC:2010(E)
3.1.3 DL-protocol-data-unit [ISO/IEC 7498-1]
3.1.4 (N)-entity [ISO/IEC 7498-1]
DL-entity
Ph-entity
3.1.5 (N)-interface-data-unit [ISO/IEC 7498-1]
DL-service-data-unit  (N=2)
Ph-interface-data-unit  (N=1)
3.1.6 (N)-layer [ISO/IEC 7498-1]
DL-layer  (N=2)
Ph-layer  (N=1)
3.1.7 (N)-service [ISO/IEC 7498-1]
DL-service  (N=2)
Ph-service  (N=1)
3.1.8 (N)-service-access-point [ISO/IEC 7498-1]
DL-service-access-point  (N=2)
Ph-service-access-point  (N=1)
3.1.9 (N)-service-access-point-address [ISO/IEC 7498-1]
DL-service-access-point-address  (N=2)
Ph-service-access-point-address  (N=1)
3.1.10 peer-entities [ISO/IEC 7498-1]
3.1.11 Ph-interface-data [ISO/IEC 7498-1]
3.1.12 primitive name [ISO/IEC 7498-3]
3.1.13 reassembling [ISO/IEC 7498-1]
3.1.14 recombining [ISO/IEC 7498-1]
3.1.15 reset [ISO/IEC 7498-1]
3.1.16 routing [ISO/IEC 7498-1]
3.1.17 segmenting [ISO/IEC 7498-1]
3.1.18 sequencing [ISO/IEC 7498-1]
3.1.19 splitting [ISO/IEC 7498-1]
3.1.20 systems-management [ISO/IEC 7498-1]
3.2 Service convention terms and definitions
This standard also makes use of the following terms defined in ISO/IEC 10731 as they apply
to the data-link layer:
3.2.1 asymmetrical service
3.2.2 confirm (primitive);
requestor.deliver (primitive)
3.2.3 deliver (primitive)
3.2.4 DL-service-primitive;
primitive
3.2.5 DL-service-provider
61158-4-12 © IEC:2010(E) – 13 –
3.2.6 DL-service-user
3.2.7 indication (primitive)
acceptor.deliver (primitive)
3.2.8 request (primitive);
requestor.submit (primitive)
3.2.9 requestor
3.2.10 response (primitive);
acceptor.submit (primitive)
3.2.11 submit (primitive)
3.2.12 symmetrical service
3.3 Common terms and definitions
NOTE Many definitions are common to more than one protocol Type; they are not necessarily used by all protocol
Types.
For the purpose of this part of IEC 61158, the following definitions also apply:
3.3.1
frame
denigrated synonym for DLPDU
3.3.2
group DL-address
DL-address that potentially designates more than one DLSAP within the extended link. A
single DL-entity may have multiple group DL-addresses associated with a single DLSAP. A
single DL-entity also may have a single group DL-address associated with more than one
DLSAP
3.3.3
node
single DL-entity as it appears on one local link
3.3.4
receiving DLS-user
DL-service user that acts as a recipient of DLS-user-data
NOTE A DL-service user can be concurrently both a sending and receiving DLS-user.
3.3.5
sending DLS-user
DL-service user that acts as a source of DLS-user-data
3.4 Additional Type 12 definitions
3.4.1
application
function or data structure for which data is consumed or produced [IEC 61158-5:2010]
3.4.2
application objects
multiple object classes that manage and provide a run time exchange of messages across the
network and within the network device]

– 14 – 61158-4-12 © IEC:2010(E)
3.4.3
basic slave
slave device that supports only physical addressing of data
3.4.4
bit
unit of information consisting of a 1 or a 0. This is the smallest data unit that can be
transmitted
3.4.5
client
1) object which uses the services of another (server) object to perform a task
2) initiator of a message to which a server reacts
3.4.6
connection
logical binding between two application objects within the same or different devices
3.4.7
cyclic
events which repeat in a regular and repetitive manner
3.4.8
Cyclic Redundancy Check
CRC
residual value computed from an array of data and used as a representative signature for the
array
3.4.9
data
generic term used to refer to any information carried over a Fieldbus
3.4.10
data consistency
means for coherent transmission and access of the input- or output-data object between and
within client and server
3.4.11
device
physical entity connected to the fieldbus composed of at least one communication element
(the network element) and which may have a control element and/or a final element
(transducer, actuator, etc.) [IEC 61158-2:2010]
3.4.12
distributed clocks
method to synchronize slaves and maintain a global time base
3.4.13
error
discrepancy between a computed, observed or measured value or condition and the specified
or theoretically correct value or condition
3.4.14
event
instance of a change of conditions

61158-4-12 © IEC:2010(E) – 15 –
3.4.15
Fieldbus Memory Management Unit
function that establishes one or several correspondences between logical addresses and
physical memory
3.4.16
Fieldbus Memory Management Unit entity
single element of the fieldbus memory management unit: one correspondence between a
coherent logical address space and a coherent physical memory location
3.4.17
full slave
slave device that supports both physical and logical addressing of data
3.4.18
interface
shared boundary between two functional units, defined by functional characteristics, signal
characteristics, or other characteristics as appropriate
3.4.19
master
device that controls the data transfer on the network and initiates the media access of the
slaves by sending messages and that constitutes the interface to the control system
3.4.20
mapping
correspondence between two objects in that way that one object is part of the other object
3.4.21
medium
cable, optical fibre, or other means by which communication signals are transmitted between
two or more points
NOTE "media" is used as the plural of medium.
3.4.22
message
ordered series of octets intended to convey information
NOTE Normally used to convey information between peers at the application layer.
3.4.23
network
set of nodes connected by some type of communication medium, including any intervening
repeaters, bridges, routers and lower-layer gateways
3.4.24
node
end-point of a link in a network or a point at which two or more links meet [derived from
IEC 61158-2]
3.4.25
object
abstract representation of a particular component within a device
NOTE An object can be
1) an abstract representation of the capabilities of a device. Objects can be composed of any or all of the
following components:
a) data (information which changes with time);
b) configuration (parameters for behavior);

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c) methods (things that can be done using data and configuration).
2) a collection of related data (in the form of variables) and methods (procedures) for operating on that data that
have clearly defined interface and behavior.
3.4.26
process data
data object containing application objects designated to be transferred cyclically or acyclically
for the purpose of processing
3.4.27
server
object which provides services to another (client) object
3.4.28
service
operation or function than an object and/or object class performs up
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