GUIDE Three-Schema Architecture
[SD-23] - Just a background reference document. Cite in the bibliography.
ANSI/SPARC and ISO Three-Schema
Architecture - Conceptual Schema and Information Base [TR9007]
- We need at least a small clause on three-schema, and these should
be references therein. This will enable us to talk about the focus
on CS, but also note the differentiation with IS and ES and the
(potential) need to map all three in a complete three-schema DD.
ANSI Information Resource Dictionary
System (IRDS) [X3.138-1988] - Very early thinking on relational
DDs. Not really relevant anymore.
ISO Reference Model of Data Management
(RMDM)  - Only useful part might be the leveling/level
pair aspects, perhaps as a point to be addressed in the guidelines.
ISO Information Resource Dictionary
System (IRDS) [10027 and 10728] - Strictly EAR-relational-based,
so its meta structures are not sufficient. However, some aspects
of the configuration management services and other similar services
might be relevant to, or referenced in, the guidelines.
ISO Portable Common Tool Environment
(PCTE) [13719-n] - Semi-object-based, but still really EAR at
the meta-structure level. This standard is fairly implementation-oriented;
in the guidelines we might refer to the PCTE architecture as an
example in the sense of potential implementation architectures,
but implementation is really outside the scope of the ITS DD standard
ISO CASE Data Interchange Format
(CDIF) [15474-n to 15479-n] - Its EAR-based meta structures are
not sufficient. The CDIF interchange syntax might be looked at
as a source for the message set template syntax expression mechanism,
depending upon the outcome of the ASN.1 discussions. Might note
(probably in the guidelines) that for any subsystem DD that uses
a more-limited, specialized modeling approach (like EAR, NIAM,
OO), the content meta models for those modeling paradigms might
well have been standardized as part of the CDIF effort and could
be a source for doing meta-meta representation and translation
using the deeper meta structures of the ITS DD standard.
IEEE Meta Data - No formal standard.
Deals mostly with custom meta data for scientific and technical
data sets. Only common aspect seems to be the use of geospatial
standards, the same ones of which are already addressed in relevant
ITS documents such as the Federal Transit Administration (FTA)
- National Transit Geographical Information Systems (GIS) Manual
and the APTS [ITS subsystem DD] Map Database User Requirements
Object Management Group (OMG)
Open Repository RFP - This is a proprietary, industry consortium
document, not a standard per se. I do not know what kind of responses
OMG received to the RFP, but the RFP clearly assumed an object-oriented
approach. We view OO as a limited, specialized approach at the
meta-structure level, but particular OO environments might be
useful as candidate IS technology corresponding to some implementations
of ITS DD CSs. On the whole, this has no real relevance to the
ITS DD standard and guidelines except perhaps in the area of the
repository services requested in the RFP. However, a brief validation
exercise indicated that these same services are addressed in the
ISO IRDS, PCTE and 11179 standards.
ISO Data Element Specification
[11179-n] - On the whole, we believe the ITS DD meta structure
approach should be reasonably consistent with this, but it should
be more formal, more explicit, better organized (allowing more
rigorous, unambiguous concept descriptions and better separation
of concepts), and will likely need to go beyond the structures
in this standard. For example, there needs to be better separation
of presentation, implementation and conceptual aspects of data,
as well as the intensional (intrinsic) and extensional (more database
oriented) attributes of data concepts. Our initial review indicates
Part 1 - This framework is useful
background and overview material on IS 11179 and is intended to
provide users of the standard a way to understand the specific
roles and interrelationships of the other five parts. Some of
the definitions might be useful for terminology, but many are
very tightly-coupled with the meta structures of IS 11179, and
may not have wide-acceptance or applicability as 'standard definitions'.
The meta structures are covered in bits and pieces in several
places, including this part and part 5. We believe they tend to
collapse certain core semantics which should be separated out,
and are insufficient for specifying the semantics of data at a
depth sufficient to support the meaningful interchange envisioned
among the ITS DDs. It should be noted that the meta structures
are more explicitly defined in a separate, draft ANSI standard
which is not yet the subject of international standardization.
Part 2 - This classification
scheme deals with the contents of a data dictionary, albeit at
a fairly general, abstract level. It is outside the scope of the
ITS DD standard and guidelines. The standard and/or guidelines
may well, however, explain and give examples of how such contents
can be populated into a DD, using the meta structures of the ITS
DD standard If particular ITS DD specifiers are interested in
such contents, there are numerous references to contents of this
kind. This particular classification scheme has not been applied,
to our knowledge, outside the SC14 community.
Part 3 - Many of the 'meta data
attributes' may be useful for data administration functions. They
should at least be addressed in the guidelines. Their formal structure
will also need to be specified in the ITS DD standard.
Part 4 - Some of these rules
for naming and specifying data elements may be good general guidelines,
and should be considered for reference or inclusion in some way
in the ITS DD guidelines. Structured semantics, however, are not
really addressed here, as most of the semantics are conveyed in
natural languages associated with the data element, not in some
explicit, formal specification. This means they would not be easily
accessible in a data dictionary or message without either extensive
human involvement, or hardcoded translation (which is effectively
what the current EDI technologies do). That's a limiting approach.
Part 5 - Naming conventions are
likely outside the scope of the overall ITS standard, although
some of the general guidelines for naming included here might
be useful for the ITS DD guidelines. The specifics of the naming
conventions here depend on the specific meta structures of IS
11179, as commented on above. This depends on whether the WG would
support, or even has a need for, a single naming convention. That
might be necessary or useful if all data is in a common registry
or at least if some data is defined in a common ITS DD across
subsystems, but in any case naming would be part of the specification
of a data concept in a data dictionary.
Part 6 - The specifics of this
part of the specification will be useful if not necessary should
the ITS DD WG agree on the need for a central registry, at least
to support data common across a number of ITS subsystems. The
general approach might be useful in the guidelines even as a way
for local subsystem DDs to exercise some control (in the data
administrative sense) over the data in their local DD.
ANSI X3L8 Metamodel for Sharable
Data - This is the draft ANSI standard noted in the discussion
of IS 11179 Part 1 above. A more detailed review of this document
will be done as part of the development of the proposed ITS DD
meta structures. It is not officially part of IS 11179, although
it can logically be considered part of that standard since this
document presents, in more detail, the meta structures presumed
to underlie IS 11179, but which are currently presented at a cursory
level in that standard. The general sense is these can be used
as one source, but they not be considered the only source.
SC14 Principles Document - Might
be a useful source for some terminology, although some definitions
may be too tied-in to the particulars of the ISO 11179 meta-model.
It is not clear whether these are entirely consistent with the
definitions in IS 11179, or even whether they supposed to be.
Proposed ITS Working Terminology
- [DEFINI~1.DOC] from Andy Schoka (softcopy) - Based on notes
from early pre-data dictionary project 'strike force' working
meeting. Good starting point to be extended by the WG.
Burt Parker's Notes from ITS
America Meeting on Data Registry and Configuration Management
- [DATA REGISTRATION NOTES.DOC] and proposed data registry overview
[REGIST~2.DOC] (softcopies). Useful for the guidelines.
Burt Parker's Technical Report
on Concept of Operations for Data Element Registry - (hardcopy).
Useful for the guidelines.
ANSI IRDS Conceptual Schema [X3/TR-14
Parts 1-2] - Cite in bibliography as background reference document
for three-schema architecture.
ISO Conceptual Schema Modelling
Facilities (CSMF)  - The normative constructs might be
considered as 'starter set' content for ITS DD's, but since this
is content, not structure, it is technically outside the scope
of the ITS DD standard. However, what we should do in the guidelines
and/or the standard is explain (and show at least one example)
of how one might use these normative constructs to describe (and
register) high-level, general concepts. These might also be input
to the classification work of the WG.
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