ISO/IEC JTC1/SC32/WG2-EM0112-013R3
Date:
2001-12-21
Source: Tim Bourne, based on document EM0112-013R2
and VIC-019C
This
proposal takes 013R2 as its starting point, and adds back those parts of
VIC019C that are not covered there and still seem to be relevant.
1.
Make
explicit, as in VIC019C, the distinction between several different choices that
must be made in assessing conformance.
2.
Make
clearer the precise meaning of levels of conformance and of obligation..
In this part of
ISO/IEC 11179, "shall" is to be interpreted as a requirement on an
implementation; conversely, "shall not" is to be interpreted as a
prohibition. If a "shall" or
"shall not" requirement is violated, the behavior is undefined. Undefined behavior is otherwise indicated in
this part of ISO/IEC 11179 by the words "undefined behavior" or by
the omission of any explicit definition of behavior. There is no difference in emphasis among these three; they all
describe "behavior that is undefined".
PROPOSER’S NOTE: Isn’t the above covered adequately in ISO Directives?
It could also be argued that Part 3 no longer specifies “behaviour” at all.
This part of ISO/IEC
11179 prescribes a conceptual model, not a physical implementation. Therefore, the metamodel need not be
physically implemented exactly as specified. However, it must be possible to
unambiguously map between the implementation and the metamodel in both
directions.
This part of ISO/IEC
11179 also prescribes a list of basic attributes for situation where a full
conceptual model is not required or not appropriate.
Conformance may be
claimed to the
either the conceptual model, or the basic attributes or both; see 6.2.
Conformance may be expressed in terms of a number
of areas, in each of which choices must be made.
The distinction between "strictly
conforming" and "conforming" implementations is necessary to
address the simultaneous needs for interoperability and extensions. This part of
ISO/IEC 11179Standard describes specifications that promote
interoperability. Extensions are
motivated by needs of users, vendors, institutions, and industries, and:
(1) are not directly specified by
this part of ISO/IEC 11179Standard,
(2) are specified and agreed to
outside this part of ISO/IEC 11179Standard, and
(3) may serve as trial usage for
future editions of this part of ISO/IEC 11179Standard.
A strictly conforming implementation may be limited
in usefulness but is maximally interoperable with respect to this part of ISO/IEC 11179Standard. A conforming implementation may be more useful,
but may be less interoperable with respect to this part of ISO/IEC 11179Standard.
The following sub-clauses define
strictly conforming implementations and conforming implementations.
The distinction between
"strictly conforming" and "conforming" implementations is
necessary for addressing the simultaneous need for interoperability and the
need for extensions. Extensions are
motivated by needs of users, vendors, institutions, and industries.
A strictly conforming
implementation:
1) shall support all
mandatory, optional and conditional data element attributes and relationships;
2) shall not use,
test, access, or probe for any extension features nor extensions to data
element attributes;
3) shall not exceed
limits nor smallest permitted maximum values specified by this part of ISO/IEC
11179; and
4) shall not interpret
nor allow the production of data element attributes that are dependent on any
unspecified, undefined, or implementation-defined behavior.
PROPOSER’S NOTE: Is “interpret” a
good word to use here? Would it be clearer to say “shall not recognize nor act
on, nor allow …”?
NOTE The use of extensions to the metamodel or the basic attributes may cause undefined behavior.
A conforming
implementation:
1) shall support all
mandatory, optional and conditional data element attributes and relationships;
2) as permitted by the
implementation, may use, test, access, or probe for extension features or
extensions to data element attributes;
3) as permitted by the
implementation, may exceed limits or smallest permitted maximum values
specified by this part of ISO/IEC 11179; and
4) may interpret or
allow the production of data element attributes that are dependent on
implementation-defined behavior.
NOTE 1: All strictly conforming implementations are also conforming implementations.
NOTE 2: The use of extensions to the metamodel or the basic attributes may cause undefined behavior.
An implementation
may conform to either of two levels of conformance to this standard:
Level 1: Only those
metadata elements, relationships and properties specified in Clause 5 are
supported and used;
Level 2: All metadata
elements, relationships and properties specified in Clause 4 are supported and
may be used.
Properties and relationships specified in this
standard are stated to be Mandatory, Optional or Conditional.
For the purpose of conformance, anything specified
as Conditional within this standard shall be treated as Mandatory if the
associated condition is satisfied, and shall otherwise be not present.
Mandatory properties and relationships shall exist,
and shall conform to the provisions of this standard. Optional properties and
relationships are not required to exist, but if they do exist they shall
conform to the provisions of this standard.
Such obligation
is enforced if and only if the Registration Status of the associated metadata
elements is Recorded or higher.
PROPOSER’S
NOTE: Does this subclause say enough? Is it useful?
The following are the registry
items and their obligation attributes in the ISO/IEC 11179-3:1994 edition of this Standard, and
the current longevity attributes:
·
Identifying: Name (mandatory), Identifier
(conditional), Version (conditional), Registration Authority (conditional),
Synonymous Name (optional, obsolete),
Context (conditional)
·
Definitional: Definition (mandatory)
·
Relational: Classification Scheme
(optional), Keywords (optional, obsolete),
Related Data Reference (optional, obsolete),
Type of Relationship (conditional, obsolete)
·
Representational: Representation Category
(mandatory, obsolete), Form of
Representation (mandatory, obsolete),
Datatype of Data Element Values (mandatory), Maximum Size of Data Element
Values (mandatory), Minimum Size of Data Element Values (mandatory, obsolete), Layout of Representation
(conditional, obsolete), Permissible
Data Element Values (mandatory, obsolete)
·
Administrative: Responsible Organization
(optional), Registration Status (conditional, obsolete), Submitting Organization (optional), Comments (optional)
Annex F relates the ISO/IEC 11179-3:attributes of the 1994 attributes to the new metamodel.
An implementation claiming conformance to this part of ISO/IEC 11179standard shall include an Implementation Conformance
Statement stating:
1)
whether it
conforms or strictly conforms (6.1);
2)
whether
conformance is to Level 1 or Level 2 (6.2);
3) what extensions are supported or
used.
Conformance needs to
be considered in the context of the roles and responsibilities of registration
authorities, as covered by ISO/IEC 11179-6: Registration of data elements.
Extended conformance
of systems requires formalisation of procedures, agreement of roles and
responsibilities between parties, and guidelines addressing use of software
products and conversions from other systems. The formalisation of these aspects
must be consistent with the conformance requirements in the above clauses, and
roles of registration authorities as set out in ISO/IEC 11179-6.
The simplification of
clause 6 results in several terms no longer being used.
The following terms
and definitions should be deleted from clause 3:
·
consume
·
generate
·
metadata entry
application
·
metadata reader
application
·
metadata set
·
produce
The following terms
and definitions are used elsewhere in the document, so need to be retained:
·
binding – used in
clause 1.3.
·
interpret – used
in clause 6.1.2 and 6.1.3, but remove the NOTE and Editor's NOTE from clause
3.1.14 (in EM008).