ISO/TR 9007:1987
(Main)Information processing systems — Concepts and terminology for the conceptual schema and the information base
Information processing systems — Concepts and terminology for the conceptual schema and the information base
This Technical Report type 3 contains the fundamental concepts and terminology for the conceptual schema, the information base, and the mechanisms involved in manipulating them. The approaches and associated languages described in the appendices A through H are intended to be explanatory only.
Systèmes de traitement de l'information — Concepts et terminologie pour le schéma conceptuel et l'information de base
General Information
Standards Content (Sample)
TECHNICAL REPORT 9007
Published 1987-07-01
INTERNATIONAL ORGANlZATlON FOR STANDARDIZATION. MEXAYHAPO,QHAfl OPTAHM3A~MR i-l0 CTAHAAPTM3A~M~*ORGANISATlON INTERNATIONALE DE NORMALlSATlON
Information processing systems - Concepts and
terminology for the conceptual schema and the
information base
IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies).
The work of preparing International Standards is normally carried out through IS0 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.
The main task of IS0 technical committees is to prepare International Standards. In exceptional circumstances a technical committee
may propose the publication of a technical report of one of the following types :
-
type 1, when the necessary support within the technical committee cannot be obtained for the publication of an International
Standard, despite repeated efforts;
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type 2, when the subject is still under technical development requiring wider exposure;
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type 3, when a technical committee has collected data of a different kind from that which is normally published as an
International Standard (“state of the art”, for example).
Technical reports are accepted for publication directly by IS0 Council. Technical reports types 1 and 2 are subject to review within
three years of publication, to decide if they can be transformed into International Standards. Technical reports type 3 do not
necessarily have to be reviewed until the data they provide is considered no longer valid or useful.
ISO/TR 9007 was prepared by Technical Committee ISO/TC 97, information processing systems.
The reasons which led to the decision to publish this document in the form of a technical report type 3 are explained in the Preface.
Ref. No. ISO/TR 9007 : 1987 (E)
U D&81.3.02
Descriptors: data processing, information interchange, factual data bases, basic concepts.
0 International Organization for Standardization, 1987 l
Printed in Switzerland Price based on 120 pages
ISO/TR 9007 : 1987 (E)
0.1. PURPOSE OF THE REPORT.
It is expected that future data base management systems will include a com-
ponent for handling conceptual schemata. This Report explains the roles and
concepts for a conceptual schema with the intention of providing a framework
for discussion and for the design of conceptual schema languages. The rules
described in the conceptual schema control to a large extent what may or may
not happen in an information system and a data base. Therefore this Report is
not limiting its attention to the conceptual schema alone, but also considers
basic concepts for the aechanl sum Involved in manipulatiw a conceptual schema
and a data base.
This Report is aimed at designer8 of information systems and data bases as well
as suppliers of conceptual schema facilities.
The provided framework will pre-
pare the way for eventual standardization in the area of data base management.
describe any particular method for using such facll-
It does not, however,
ities. In the meantime, the general principles in this Report can be used to
evaluate emerging DBMS facilltleso
The approaches and associated languages described in appendices to the Report
are intended to be explanatory only and are not ipso facto candidates for a
standard conceptual schema language.
0.2. STRUCTURE OF THEi REPORT.
The main body of the Report (chapters one through four) contains the fundamen-
tal concepts and terminology for the conceptual schema, the information base,
and the mechanisms involved in manipulating them.
Chapter one gives an introduction to the subject, mentions the origins of some
and discusses some major topics. In particular,
ideas developed in the Report,
it explains what a conceptual scheam is used for, its roles, aad requirements
for a conceptual schema facility.
provides definitions- of the concepts
Chapter two explain8 fundamental concepts,
and tenas and develops some of the consequences of those concepts and deflni-
tlons. Both static and dynamic aspects of the information system are considered
Some readers may wish to skip this chapter on the first reading.
and explained.
some aspect8 of implementation. In particular, prln-
Chapter three discusses
ciples are formulated for the contents and scope of a conceptual schema, and an
information system architecture based on three levels is outlined.
to information modelling and manipulation
Chapter four reviews some approaches
The approaches selected for illustration are outlined in more
for data bases.
detail in appendices to the Report.
,
ISO/TR 9007 : 1987 (E)
Severs1 appendices have been added to the Repmt as follows:
Appendix A gives a glossary of the terms and definitions.
Appendix B provides an example situation to be described in information model-
ling approaches.
Appendix C gives a syntax notation to be used for defining grammar8 of example
conceptual schema languages e
Appendix D outlines Entity-Attribute-Relatianship approaches.
Appendix E demonstrates Binary and Elementary H-ary Relationship approaches.
Appendix F discusses Interpreted Predicate Logic approachem.
Appendix G elaborates on expressing dynamic rules and constraint8
in conceptual
schemata.
Appendix H presents thought Od interacting with information
systems
exaaplea of pemissi ble action descriptions.
0.3. STATUS OF THE REPORT.
This Report is an IS0 Technical Report of tppe 3. It fs the Working Group’cr
first response to ita 1 of its Program of Work.
As such it is a statement of
the Uorklng Group’s current view on concepts for conceptual schemata and infor-
mation bases. Considering the rapid development in data base technology and
application8 pomible, also takingi into account the requirments for diatri-
buted data base systems and related data camwnication facilities, periodic
revisions of the Report are to be expected.
0.4,. REFERENCES.
A
[l) MURRAY, 3.A.H. et al.
‘The Oxford English Dictionary’ with supplements,
Clarendon Press, 1933 - 1977.
ISO/TR 9007 : 1987 (E)
Chapter 1. INTRODUCTION TO THE CONCEPTUAL SCHEMA AND THE wFO&MTION BASE.
1.1. The ANSI/SPARC framework.
1.2. The universe of discourse. 10
1.3. Describing the universe of discourse.
1.4. Static and dynamic aspects of a conceptual schema and informa-
tion base.
1.5. Interaction between the real world and an information system.
1.6. The roles of users and information processors.
1.7. Guideline8 for the description of a universe of discourse.
1.8. Guidelines for the contents of a conceptual schema*
1.9. Roles for a conceptual schema.
1.10. Requirements for a conceptual schema facility.
1.11. References.
Chapter 2. FUNDAMENTALS FOR A CONCEPTUAL SCHEMA AND AN INFORMATION BASE. 21
2.1. General concepts and definitions.
2.2. Basic concepts and definitions for actions on the conceptual
schema and infotmatioa base.
2.3. The behaviour of an information processor. 31
2.4. Xnserting a conceptual schema - the minimal conceptual schema. 33
2.5. Behaviour rules for the environment.
2.6. Static and dynamic rules and constraints.
2.7. Expressing tules and constraints.
2.8. Co-ordination of permissible actions.
2.9. References.
Chapter 3. SOME CONCEPTS AND PRINCIPLES FOR IMPLEMENTATION.
3.1. Principles for the contents and scope of a conceptual schema.
3.2. Principles for the description of a universe of discourse. 47
3.3. Abstract syntax for a conceptual schema and information base.
3.4. Semantics of a conceptual schema and information base.
3.5. Principles for the composition of conceptual schemata.
3.6. The Three Level Architecture.
3.7. Information Resource Dictionary Systems (IRDS) Model.
3.8. The conceptual schema in the context of current DBMS implemen-
tation.
3.9. Correspondence of the Three Level Architecture for information
systems and the Reference Model for Open Systems Interconnec-
tion.
3.10. References.
Chspter 4. OVERVIEW OF SOME MODELLING APPROACHES. 63
4.1. Introduction. 63
4.2. Review of some approaches.
4.2.1. Entity attribute relationship approaches. 66
4.2.2. Binary and elementary n-ary relationship approaches.
4.2.3. Interpreted predicate logic approaches.
4.3. Translation of approaches to current data base technology.
6.4. References.
ISO/TR 9007 : 1987 (E)
Appendix A. GLOSSARY OF TERMINOLOGY M DEFINITIONS.
Appendix B. EXAMPLE UNIVERSE OF DISCOURSE. 77
B.1. Introduction. 77
8.2. Rules, etc. for the universe of discourse.
B.3. Some things and happenings in the relevant entity world.
Appendix C. THE PASCAL SYNTAX NOTATION.
Appendix D, THE ENTITY - ATTRIBUTE - RELATIONSHIP APPROACHES.
D.1. Emphasis of the approaches. 83
D.2. Primitive concepts of the approaches* 84
D.2.1. The basic concepts.
D.2.2. Abstraction concepts. 84
0.2.3. Characteristics of relationships. 86
D.3. Grammar and semantics.
0.4. Graphic formalism.
D. 5. Hodelling.
0.5.1. Some pragmatic modelling rules.
0.5.2. Formal rules for mdelling.
D. 6. Example conceptual schema.
D.6.1. Graphic representation.
D.6.2. Language example.
D.7. Check list for the conceptual schema.
0.8. Mapping of an EAR conceptual schema to a network data base
schema and a relational data base schema.
D.9, References.
Appendix E. TIiE BINARY RELATIONSHIP APPROACHES.
E.1. Emphasis of the approaches.
E.2. Primitive concepts of the approaches.
E.3. Grammar and semantics.
E.3.1. The language and its relation to the universe of
discourse. 111
E.3.2. Formal syntax.
E.3.3. Semantics.
E.4. Graphic formalism.
E.4.1. Linguistic object types.
E.4.2. Binary relationship types.
E.4.3. Constraints having a diagrammatic representation.
E.4.4. Some examples of the graphic formalism symbols.
E.5. Xodelling.
E.6. Example conceptual scheme
E.6.1. Graphic representation.
E.6.2. Language example.
E.7. Check list for the conceptual schema.
E.8. References.
ISO/TR 9007 : 1987 (E)
Appendix F. THE INTERPRETED PREDICATE LOGIC APPROACHES.
F.1. Emphasis of the approaches. 135
F.2. Primitive concepts of the approaches.
P.3. Grammar and semantics. 137
F.3.1. Abstract syntax. 137
F.3.2. Concrete syntax.
P.3.3. Semantics.
F.4. Graphic formalism.
P.S. Modelling.
F.S.l. Cla8sification of axioms.
P.5.2.Gonstruct8.
P. 6. Example conceptual schema.
F.6.1. Graphic representation.
F.6.2. Language example.
F.7.Xh&ck list for the conceptual schema.
F.8. References.
Appendix G. EXAMPLES OF DYNAMIC RULE DESCRIPTION.
G.L. Introduction. 171
G.2. State-oriented descriptions. 171
6.3. State-oriented description of rules in the example conceptual
schema. 171
6.4. State independent rules in action-oriented descriptions. 172
G.5. State dependent rules in action-oriented descriptions.
G.6. Action-oriented description of rules in the example conceptual
schema.
Appendix H. EXAMPLES OF CO-ORDINATING PERMISSIBLE ACTIONS. 177
H.1. Interaction between environment and information system.
8.2. Some implementation considerations for permissible actions. 178
H.3. Describing pemissible actions in the example conceptual schema. 179
R.4. References.
ISO/TR 9007 : 1987 (E)
THE HELSINKI PRINCIPLE.
These utterances are’ to be interpreted (recursively) as international English
utterances [l]:
depends upon the prior existence
hy meaningful exchange of utterances
set of semantic and syntactic rules. The recipients of
of an agreed
the utterances must use only these rules to interpret the received ut-
if it is to mean the same as that which was meant by the
terances,
utterer.
(IS0 TC97/SCS/WG3 - Helsinki 1978)
"THE METAPHOR OF THE SEARCHLI(XTS" on universes of discourse.
This page intentionally left blank
lSO/TR 9007 : 1987 E)
CHAPTER he INTRODUCTION TO THE CONCEPTUAL SCHEMA AND THE INFORMATION BASE.
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1.1. THE ANSI/SPARC FRAMEWORK.
The reports of the ANSI/XB/SPARC DBSG [l, 21 identified the need for a concep-
tual schema in the context of a three-schema framework for data base management
SyStelllSe
Subsequent papers [3, 4, 5, 6, 71 have emphasized the importance of a concep-
tual schema to users and designers of data base systems. In this context, a
conceptual schema comprises a unique central description of the various informa-
tion contents that may be in a data base. This includes the description of what
actions, such as changes and retrievals, are permissible on the information
The data base itself may be implemented in any one of a number of poss-
content.
ible ways. Users and application programs may view the data in a variety of
each described by an external schema.
Each external schema is therefore
ways 9
derived from the common conceptual schema. The physical storage structure that
may be in use at any given time is described by an internal schema that is also
derived from the conceptual schema.
The conceptual view, as meant by ANSI/SPARC, concentrates on the meaning of the
It is the conceptual schema that describes this view. The external
informatioL
- that represent the information to
views concentrate on the forms - the data
the outside. These are described in the external schemata. The internal view
concentrates on the internal physical representation of the data inside the com-
puter system and is described in the internal schema.
Such a three-schema framework is widely, but not yet universally, accepted. It
is assumed in this report. Furthermore, it may be noted that the conceptual
schema concept is valuable in other environments than a three-schema framework.
schema also plays a key role in
It is widely acknowledged that the conceptual
systems analysis and data base design. One may therefore ask whether it should
Should the conceptual schema be primarily an en-
be biased to one or the other.
or should it serve as a
terprise model, resulting from the systems analysis,
user views and the physical data base design? We believe
focal point between
that it should play both roles in the next generation of DBMS.
We believe the data base user will benefit from the clear separation of the in-
formation meaning from the external data representation and the internal physi-
A clear methodology for producing a conceptual schema
cal data storage layout.
of an information system to improve his systems
would help the implementor
it into data base design in
even if a manual step of translating
analysis,
terms of an existing DBMS were then required.
ISO/TR 9007 : 1987 (I3
the conceptual schema in broad terms. Resides, the
The ANSI reports introduced
is sometimes used for data base aspects which are not
term "conceptual schema"
Therefore, elaboration of the conceptual schema's objec-
at all ConceptuaL
form, and content is needed. What a conceptual schema must in-
tives, roles,
which appropriate modelling concepts are to be used in it, and the exact
clude,
are the major subjects of this Report.
role it plays in data bases,
1.2. THE UNIVERSE OF DISCOURSE.
In the past, data processing systems were often designed so as to provide all
However,
users with the same set of capabilities or functions. this uniform
functional view is not adequate to construct today's data base systems. A
different functional requirements concur-
single data base may support quite
rently, or at different times, during its existence.
base environment is that common data is
The prime characteristic of the data
shared between many users of a single system. By sharing common data, these
users establish a dialogue with each other through the system. Clearly, if this
communication is to be useful and reliable there must be some common under-
Since it may happen that
standing of the information represented by the data.
two users never meet, this common understanding must refer to something exter-
This common understanding must be recorded and in order to
nal to both of them.
establish a dialogue a common predefined established grammar is needed.
We will call those things and happenings to which the common understanding of
the represented information refers the universe of discourse. Universes of dis-
or abstract like the organizational
course may be concrete like an inventory,
They even may be hypothetical like Wonderland which
structure of an enterprise.
was visited by Alice.
In this Report we will take an (informal) naive realism approach to universes
of discourse.
The typical universe of discourse is perceived as containing real and abstract
objects, which we will call entities. It can be perceived as also containing
classes of entities, e.g. persons, departments, and dates. This classification
is based on similarity and takes into account characteristics common to several
The selection of characteristics for grouping the entities into
entities.
the choices will be made pragmatically, based on the
classes is arbitrary;
purpose of the universe of discourse.
Some general properties to which entities adhere, that classify entitfes, that
in the universe of discourse are also perceived
associate entities, etc.,
(e.g. persons are not departments, a person may be assigned to no more than one
These may be informally described as "classifications", "rules",
department).
"laws" or "constraints" about the state of affairs and behaviour of entities in
the universe of discourse.
what is considered to be part of the universe of discourse will be
In general,
the selected things and happenings may change with
time-dependent, that is,
time. This will be equally true for the classifications, rules, laws, etc; how-
it is likely that the rate of change of these will be relatively slow
ever,
compared with that of the former.
ISO/TR 9007 : 1987 (E)
1.3. DESCRIBING THE UNIVERSE OF DISCOURSE.
There are in fact two systems of interzc+: the universe of discourse and a data-’
processing system which contains a linguistic representation of that universe
of discourse. Following common usage we say that information about the universe
of discourse "describes" or "models"
that universe of discourse. We want, how-
to emphasize that the description process may be in fact a very complex
ever,
task calling for creative analysis and iterative refinement.
Without prejudging its physical representation we consider that the information
contained in the data processing system describes the universe of discourse. A
concrete physical representation of this information will be called a data
base. We will use the term data base system for a data processing system deal-
ing with a data base. It is possible for the data base system itself to be one
of the subjects being described, in which case the data base system would be in-
cluded in the universe of discourse. However, to simplify the discussion, we
will generally assume that the data base system is disjoint from the universe
of discourse, although this is not necessarily the case.
It is the classifications, rules, etc., that are of primary interest to a sys-
tems designer designing a data base system. In analysing the universe of dis-
course, it is these things he will want to identify, discuss with users and
describe. In recording them he will actually create a "skeleton" description of
the universe of discourse, the conceptual schema.
In this way the conceptual
schema describes which entities can possibly exist in the universe of dis-
course, that is, which entities exist, have existed, or might ever exist. In
the same sense it describes what facts and happenings are possible for those
entities or, if relevant, are required for them.
We assume it will be held in a
formal representation within the data base system.
We also want to record all other relevant information which describes the en-
tities that are considered to be of interest and their actual state of affairs h
at a specified instant or period of time (usually "now"). We call this further
information the information base.
Although description necessarily will have a representation form to make
each
the description communicable, it is the interpretation of this representation
(the meaning of the description) which interests us in the first place. The
form, although not irrelevant, is considered to be of secondary
representation
"information" when we want to emphasize our
importance. We will use the term
will use the term "data" when we want
interest in this interpretation. We to
concentrate on the representation forms of the information.
to consider the information describing a uni-
At this point it may be useful
verse of discourse within the context of an ANSI/SPARC framework: We consider
both the conceptual schema and the information base to be at the conceptual
level, providing a conceptual view of the information about the universe of dis-
course.
%een user of the system (the strings of
The data base or parts thereof as
bY a
data) we consider to be at the exte-.tl;al level giving an external view on the in-
The internal storage forms within a
form&ion about the universe of disc:>urse.
computer we consider to be at the internal level being the internal view of the
information about the unfverse of discourse. For the external and internal
views the representation forms are of primary interest. The interpretation of
those forms is, of course, the interpretation meant in the conceptual view.
ISO/TR 9007 : 1987 E)
Summarizing we have now identified:
Universe of discourse:
The collection of all objects (entities) that ever have
been, are, or ever will be in a selected portion of a real
world or postulated world of interest that is being de-
scribed.
Conceptual schema:
The description of the possible states of affairs of the uni-
the classifications, rules,
verse of discourse including
of the universe of discourse.
laws, etc.,
Information base:
The description of the specific objects (entities) that in a
specific instant or period in time are perceived to exist in
the universe of discourse and their actual states of affairs
that are of interest.
Precise definitions for the above concepts will be given in chapter 2e
conceptual
schema
information
R
Figure 1.1. Describing the universe of discourse.
is illustrated in figure lel; the two numbered pro-
The description process
cesses are:
abstraction, generalization, establishing
1: Classification,
about the universe of discourse and recording
rules, etc,
describing a (shared) mental
them. This is a human process,
model of the universe of discourse.
S
and happening about the universe of dis-
2: Recording facts
entities ac tually are of interest,
course including
ISO/TR 9007 : 1987 (E)
The conceptual schema describes the general rules, etc, of the universe of dis-
course, which, to a great extent, may govern its behaviour. These rules de-
scribed in the conceptual
schema therefore also control what may or may not
occur in the information base. It is for this reason that we do not limit our
attention to the conceptual schema and information base; we will also consider
the mechanisms involved in manipulating the contents of the information base
and the conceptual schema.
1.4. STATIC AND DYNAMIC ASPECTS OF A CONCEPTUAL SCHEMA AND INFORMATION BASE.
Much of the past work on concepts for the conceptual schema has been concen-
trated on the static aspects, that is, on defining the concepts to be used to
describe valid states of a conceptual schema and information base.
However, the set of concepts for the conceptual
schema should also cover the
dynamic aspects. Firstly, the conceptual schema may change to correctly reflect
changes in the selected portion of a real or postulated world. Secondly, dy-
involved in describing those manipulations which are needed
namic aspects are
to make known part or all of the conceptual schema and information base.
In some cases, the time scales of changes within the universe of discourse. and
in the conceptual schema and information base need
the corresponding changes
changes in the universe of discourse may be re-
not be tied closely together:
corded in the conceptual schema and information base retrospectively and even
in a different sequence. In other cases, the time scales are so closely related
to each other that the conceptual schema and information base necessarily
become part of the universe of discourse; especially in these cases the descrip-
tion of this interaction must also be part of the dynamic aspects.
static and dynamic aspects, and the
No clear boundary has been defined between
boundary may well be found to vary between different approaches or even to be
Some of the ideas introduced on this subject in the
non-existent in some cases.
present Report have not yet been the subject of wide debate, but may at least
In particular it is not clear
serve to indicate areas deserving further study.
whether different sets of concepts should be used to describe static aspects
at least for some approaches, the same set of
and dynamic aspects, or whether,
concepts may fulfil both purposes.
1.5. INTERACTION BETWEEN THE REAL WORLD AND AN INFORMATION SYSTEM.
and information base is totally static unless something
A conceptual schema
That something we will call an information pro-
operates on it to cause change.
cessor. We will define an information system as consisting of a conceptual
and an information processor.
schema, an information base,
to produce change in the information base or
An information processor operates
conceptual schema only on receipt of a message. A message contains information
Messages originate from a part of the real world re-
and/or expresses commands.
which may be disjoint from, or overlap with, the
ferred to as the environment,
On receipt of an appropriate message containing a com-
universe of discourse.
mand an information processor may also operate to make known, by means of a
in the conceptual schema and information base. For
message, information present
further details see chapter 2.
ISO/TR 9007 : 1987 E)
environment
Figure 1.2. Information system and environment.
The information system is distinguished from the environment in the following
way:
0 The information system is a formal system, the environment
as a whole is not SO.
o The behaviour of the information system is completely
defined by behaviour rules and constraints which are
established, directly or indirectly, by the environment. The
information system on its own initiative never establishes
rules for the environment.
o An information system, being fully predictable, is unable to
deviate from the rules or constraints. The environment can
deviate from its rules.
the information system together with the environment
Although we may consider
this latter system may not be formal or
to be parts of an encompassing system,
the term information system as above,
fully predictable. Therefore we use
- the users of an information system.
excluding the environment
1.6. THE ROLE OF USERS AND INFORMATION PROCESSORS.
The users of an information system can be machines or other systems as well as
human beings. A user is anybody or anything that issues commands and messages
from the information system. As
to the information system and receives messages
such they are part of the environment. Some users also have the authority to
establish behaviour rules or constraints for the information system.
ISO/TR 9007 : 1987 (EI
An information processor transfers messages between the environment and the in-
formation base or conceptual schema, as explained above. In doing this it has
no initiative of its own; it can only behave exactly as specified by the rules,
the whole rules, and nothing but the rules.
Normally an information processor will be a computer system or some parts there-
of, but human beings can also play the role of an information processor, pro-
vided they do not deviate from prescribed rules or act on their own initiative.
on the other hand, can act as users of an information sys-
Computer systems,
tem.
An example is a network of information systems communicating with each
other. If each has a set of rules which is independent of the others, then each
plays the role of user of the other information systems. We therefore conclude,
that the role determines whether something must be regarded as a user or as an
information processor.
The above formulation of users and information processors in terms of roles
implies that the environment and the information system need not necessarily be
disjoint, Similarly, if the information base contains information about the
the environment and the universe of discourse
users of the information system,
will not be disjoint. However, even if they are not disjoint they will always
be distinguishable from each other.
1.7. GUIDELINES FOR THE DESCRIPTION OF A UNIVERSE OF DISCOURSE.
Sometimes in the literature on various modelling methods for information sys-
tems and conceptual schemata, no clear distinction is made between the things
nor between the information meaning and the
and the description of the things,
data representation.
This stems partly from the origins of some approaches which are in effect the
data modelling techniques of the early seventies. Partly, however, the reason
for this is a debate on fundamentals, which is still going on. The difference
is found in whether the conceptual schema must be defined in terms of entities
in the universe of discourse itself and states of affairs about them, or in
found in the information base describing the
terms of descriptive constructs
entities of interest in the universe of discourse. Either view is possible and
can be presented systematically.
It is most important to note though that the two alternative views above cannot
be indiscriminately mixed in the same discussion without leading to confusion,
paradox, and error. It is unfortunate but true that many variants of modelling
and as described in the literature, suffer from
approaches, both in practice
precisely these problems.
The current work of WG3 is based on the assumption that the conceptual schema
and the information base should describe the conceptual view. This implies that
is defined in terms and constructs referring to things in
the conceptual schema
of affairs about those
the universe of discourse itself and expressing states
things.
used in a conceptual schema and information base should be
The constructs
theoretical foundation, However,
based on the fundamentals of formal logic as
forms of these fundamen-
how closely they must follow the spirit and notation
It is quite possible to limit them
tals is a subject of further investigation.
to elementary constructs expressing these fundamentals. However, it will be
ISO/TR 9007 : 1987 (E)
always possible to define, upon these fundamentals, a variety of more complex
that may be more convenient or efficient for
constructs (-macro constructsn),
describing various aspects of a universe of discourse.
The choice of specific macro constructs is based on practical arguments such as
ease of understanding and use. That choice is considered to be dependent on the
application area of the information system for which a conceptual schema and
information base has to be provided.
As already stated, it is important to distinguish carefully between the en-
tities and their descriptionse In these descriptions entities are usually
identified by names that refer to those entities. This includes synonyms -
different names refering to the same entity - and homonyms - identical names
refering to different entities. The relevance of this distinction, not only for
but for human communication in general, has
information systems in particular,
been well-known in language philosophy and linguistics for a long time. There-
fore the constructs should provide for synonyms and possibly cope with homonyms.
The conceptual schema not only describes the static aspects and dependencies of
but also the dynamic aspects. This determines what
the universe of discourse,
manipulations of the descriptions are allowable as well as what descriptions
may be present in the conceptual schema and information base. Therefore it may
be clear that constructs have to be available both for the descriptions and for
their manipulation in the information system.
The subject is elaborated further in chapter 3.
1.8. GUIDELINES FOR THE CONTENTS OF A CONCEPTUAL SCHEMA.
Since the selection of what are considered to be general classifications,
of the universe of discourse is to a certain extent arbitrary, it
rules, etc.
follows that the choice of which should be described in the conceptual schema
In prac-
and which in the information base is arbitrary to a similar extent.
tice, however, the systems designer might consider various factors in deciding
the boundary of the conceptual schema. These might include:
s, variables) in the universe of dis-
- describing classes (
type
course rather than i ndiv iduals (instances),
ncept s that are less subject to chang e rather
- describing co
that are cha nging more freque
than concepts ntly 9
- inclusion of rules or constraints having wide influence on
the behaviour of the universe of discourse (and therefore on
the behaviour of the conceptual schema and information base)
rather than narrow influence.
principles for
At all times the following general the conceptual schema should
be observed:
* 100 Percent principle:
All relevant general static and dynamic aspects, i.e. all
of the universe of discourse should be
rules, laws, etc.,
described in the conceptual schema. The information system
ISO/TR 9007 : 1987 (EI
cannot be held responsible for not meeting those described
elsewhere, including in particular those in application
programs.
* Conceptualization principle:
A conceptual schema should only
include conceptually
relevant aspects, both static and dynamic, of the universe
of discourse, thus excluding all aspects of (external or
internal) data representation, physical data organization
external
and access as well as all aspects of particular
user representation such as message formats, data struc-
tures, etc.
A more detailed discussion may be found in chapter 3.
leg. ROLES FOR A CONCEPTUAL SCHEMA.
A fundamental impact of a conceptual schema is that the concepts used harmonize
- and to a certain level make possible - human communication. Moreover, these
concepts will influence the methods and results of analysing organizations and
their information needs. In a way, a conceptual schema constitutes a general
agreement concerning how to perceive a universe of discourse.
This agreement
but supports the evolution of applications over their life
may alter over time,
cycles as well as changes of this agreement itself (cf. The Helsinki Principle),
A conceptual schema is intended to properly describe the behaviour of a uni-
verse of discourse. Therefore the rules given therein, naturally, restrict
possible evolutions and manipulations of the description of the universe of
of the conceptual schema itself as well as of the information
discourse, i.e.
base.
Mainly for reasons of human convenfence and efficiency, different users within
the environment of a common information system will use different forms of ex-
ternal data representing the information. At the same time, for reasons of
Internal data organizations will be
machine and storage handling efficiency,
designed and used that may or may not differ from those external forms. In this
the conceptual schema enforces preservation of meaning in transforma-
context,
tions between the various data representations and defines the interpretation
of these representations.
what is outlined in the previous sections, the
Therefore, and considering
following fundamental roles for a conceptual schema have been identified:
To provide a common basis for understanding the general be-
1.
haviour of the universe of discourse;
To define the allowed evolution and manipulation of the in-
2 l
formation about the universe of discourse;
for interpretation of external and inter-
TO provide a basis
3 l
which represent the information about
nal syntactical forms
the universe of discourse;
a basis of mappings between and among external
To provide
4 l
and internal schemata.
ISO/TR 9007 : 1987 (E)
1.10, REOUIREMENTS FOR A CONCEPTUAL SCHEMA FACILITY.
It is anticipated that the data base management systems developed 1n the future
will include a component for handling a conceptual schema definition which till
fulfil the roles mentioned in the previous section. In the course of time, pro-
vision of such a component should become a standard requirement.
To fulfil the roles indicated above, a conceptual schema facility must satisfy
the following requirements:
le It must provide basic concepts which are suitable for ad-
equately describing both the static and dynamic aspects of a
universe of discourse and ipso facto its description in
terms of a conceptual schema and information base.
2. It must provide a language in which a conceptual schema can
be expressed so as to be readily understandable to a user of
the facility.
ovid ea language for precisely communicating a con-
3 l It must
Pr
ceptual SC .hema to a COUlpUteL
4. It should provide for easily modifying the conceptual schema
to reflect changes in the general classifications, rules,
of the universe of discourse, and for predicting
laws, etc.
the direct consequences of such changes.
5. The views of the information that different users wish to
see are limited to those which do not contradict the asser-
tions in the conceptual schema. If such external schemata
are subject to change, the facility should be such that this
should not affect the conceptual schema.
6. The conceptual schema should be kept invariant by the facil-
ity with respect to changes in the internal (physical) repre-
sentation of the data within a computer.
The two languages mentioned in 2 and 3 may be the same but are not necessarily
so. For the former purpose an additional graphic notation may be helpful,
as a minimum must be met by any candidate conceptual
These six requirements
schema facility.
ISO/TR 9007 : 1987 (E)
1.11. REFERENCES.
'Study Group on Data Base Management Systems:
[l] ANSI/X3/SPARC,
Interim Report 75-02008',
In: ACM SIGMOD Newsletter, FDT, Vol 7, No. 2, 1975.
[2] TSICHRITZIS, D., and KLUG, A. (eds.)
'The ANSI/X3/SPARC DBMS Framework. Report of Study
Group on Data Base Management Systems',
AFIPS Press, Montvale NJ, 1977.
'Role and Composition of a Conceptual Schema in an
[3] BSI/DPS13/WGl,
Overall DBMS Architecture',
1976.
'Study of Users Requirements',
[4] AFNOR/Z6/SC5,
1977.
'The Next Five Years in Data Base Technology',
[5] NIJSSEN, G.M.
In: Infotech State of the Art Conference, London,
1977.
'A framework for advanced mass storage applica-
[6] NIJSSEN, G.M.
tions',
In: Medinfo 80, Proceedings of the Third World
Conference on Medical Informatics, Tokyo 1980,
North-Holland Publishing Company, 1980.
'On the conceptual approach to data bases'
[7] FALKENBERG, E.
Conference on Data Bases,
In: International
Aberdeen 1980, Heyden and Son, London, 1980.
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lSO/TR 9007 : 1987 E)
FUNDAMENTALS FOR A CONCEPTUAL SCHEMA AND AN INFORMATION BASE,
CHAPTER 2.
------11----------------------------------------------------------- we-- -
---------------------------------------------------------------,----.-
2.1. GENERAL CONCEPTS AND DEFINITIONS.
We propose in this Report concepts and terms to be generally used in designing,
describing, and using conceptual schemata and information bases.
Some of the
terms defined in this Report are already found throughout the data base litera-
ture, occasionally with conflicting meaning. The purpose of this chapter is to
describe the fundamentals and to give short, precise, although intentionally
wherever possible conforming
informal, definitions of the concepts and terms,
with the meaning most closely associated with natural language [l]; e.g. the
is to be interpreted in ordinary language sense. The defini-
term "real world"
tions are embedded in explanatory prose to inform the reader of the basic con-
cepts and intent of our view of the conceptual schema and information base. The
definitions themselves will be summarized in a glossary of terms in appendix A
to this Report.
We start by assuming that it is possible to select a portion of a real or hypo-
thetical world that is describable in some chosen precise and formally defined
language. All thdngs we perceive or assume to exist in this selected portion of
a world are called entities:
ENTITY
Any concrete or abstract thing of interest, including associ-
ations among things.
\
if we select a portion of a world as described in appendix B and
For example,
in which a certain Registration Authority is assumed to be interested, then
entities are the car Ford Mustang PCXX999, the person Mr. Johnson, the date 29
A particular example of an abstract entity is an association
January 1975, etc.
among other entities, e.g. the "ownership" of the car PCXX999 by Mr. Johnson.
world we are interested in
In perceiving or imagining the selected portion of a
we may conceive all kinds of states of affairs concerning one or more entities
therein. Examples are:
II
The car XXX999 is of model Mustang
-
The car PCXX999 has got registrationnumber GMF 117
-
The car pCXX999 is distributed by Ford to Smith's garage on
29 January 1975
-
Garages sell cars to persons
-
Ford is a car manufacturer
We call such states of affairs propositions:
ISO/TR 9007 : 1987 El
PROPOSITION
A conceivable state of affairs concerning entities about
which it is possible to assert or deny that such a state of
affairs holds for those entities.
A
proposi tion can concern one entity, several individual entities,
groups of
en tities, etc.
In practice the distinction is often made between propositions about the actual
state of individual entities, and propositions about which behaviour of en-
tities may or may not be permissible or possible. The words "rule" and "con-
straint" refer in particular to propositions of this latter kind.
Actually It will be descriptions of the propositions - sentences - that enable
us to discuss entities and their states of affairs at all - that is, to ex-
change information about entities by describing propositions which hold for
them:
SENTENCE
A linguistic object which expresses a proposition.
LINGUISTIC OBJECT
A grammatically allowable construct in a language.
Note, that linguistic objects may be considered entities.
Sentences consist of ter
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