Fellow Working Group Members:

Attached please find an updated version of "Candidate ITS Working Terminology for Data Dictionaries and Message Sets," dated 4 March 1997. This version accommodates a valuable contribution from Paul Hawes, the editor of ANSI X3.285 and participant in ASC X3L8, Data representation. The material regarding message-related definitions has been reworked (thank you Tom Kurihara) and supplemented so as to facilitate our next discussions in the Working Group specifically dealing with message set templates. Consider reviewing these definitions in preparation for the meeting. In order to provide a perspective, I should say that once this Working Group agrees with these definitions, the paper is intended to be floated to the CSO participants in response to a CSO action item.

See you at the meeting,

Regards,

Andy Schoka

Abstract Syntax Notation One (ASN.1):

In general, ASN.1 refers to a standard notation for the definition of data types and values along with encoding rules that produce a transfer syntax for these values. The notation is specified in ISO/IEC 8824: Specification of basic notation. The encoding rules are specified in ISO/IEC 8825: ASN.1 Encoding Rules. ASN.1 is used for describing system interfaces. It encompasses both a methodology (8824) for specifying the syntax of interface data and encoding methods (8825) for producing actual messages to be exchanged across the interface.

attribute:

A characteristic of an object or entity. (ISO 11179-3)

attribute value:

A specific occurrence of an attribute. For example, "blue" is an attribute value for the attribute "color".

context:

A designation or description of the application environment or discipline in which a name is applied. (ISO 11170-3)

data:

A representation of facts, ideas, or instructions in a formalized manner suitable for communication, interpretation, or processing by humans or by machines. (This definition refers to a group of facts taken as a unit, thus it is used with a singular verb.)

data composite:

A collection of data elements treated as a unit.

data concept:

The human perception of a property of an object set, identified and described independently of any particular representation.
data dictionary:

A specialized type of database containing metadata, which is managed by a data dictionary system; a repository of information describing the characteristics of data used to design, monitor, document, protect, and control data in information systems and databases; an application of data dictionary systems (DoDD 8320.1)

data dictionary system:

A software system for defining, creating, updating, processing, and using data dictionaries.

data element:

1. A unit of data for which the definition, identification, representation, and permissible values are specified by means of a set of attributes. (ISO/IEC 11179-3) 2. A single unit of data that in a certain context is considered indivisible. It cannot be decomposed into more fundamental segments of data that have useful meaning within the scope of the enterprise.

data element dictionary:

An information resource that specifies, defines, and lists all relevant data elements. (ISO/IEC 11179-3)

data model:

A description of the organization of data in a manner that reflects an information structure.

data registry:

A place to keep characteristics of data that are necessary to clearly describe, inventory, analyze, and classify data. A data registry supports data sharing with cross-system and cross-organization descriptions of common units of data. A data registry assists users of shared data to have a common understanding of a unit of data's meaning, representation, and identification.

data unit:

A single kind of data for which the identification and description are identical for all occurrences. It may be a data composite or a data element.

datatype:

A category used to classify the collection of letters, digits, and/or symbols to depict values of a data element based upon the operations that may be performed on the data element.

definition:

A statement of the essential meaning of a person, thing, word or word group, or a sign or symbol.

description:

Words representing a person, thing, word, or word group, or a sign or symbol intended to give a complete conceptual image. May include a definition along with other characteristics.

information repository:

A database application that contains information about systems, organizations, networks, business processes, information flows, and other facts about the enterprise's information resources.

message:

In data communications, any thought or idea expressed in a form suitable for transmission by any means of communication.
message body:

See message structure.

message catalog:

An organized list of messages, with reference to their locations and relationships to other messages. Each message catalog shall be registered.

message format:

A predefined structure and order of message elements for use in ITS messages. Each message format shall be registered.

message header:

See message structure.

message list:

A finite, defined set of messages for use in representing ITS dataflows. A message list shall be registered.

message structure:

The general layout and components of a message consisting of a message header, message body, and message trailer. The message header includes data about the entire message. The message body includes information relating to the function and dataflow represented. The message trailer includes data that marks the end of the message.

message template:

A reference pattern for the contents of each of the three message components which may be used in its entirety or adapted for communicating among ITS entities and components. See message structure. Each instance of the use of a message template shall be registered.

message trailer:

See message structure.

object class:

A set of concepts, abstractions, or things in the natural world that can be identified with explicit boundaries and meaning and whose properties and behavior all follow the same rules.

Open Systems Interconnection--Reference Model (OSI-RM):

An abstract description of the digital communications between application processes running in distinct systems. The model employs a hierarchical structure of seven layers. Each layer performs value-added service at the request of the adjacent higher layer and, in turn, requests more basic services from the adjacent lower layer. (FS-1037C)

permissible value:

One member of the allowed representations of a data element.

profile:

A set of one or more base standards and, where applicable, the identification of chosen classes, conforming subsets, options and parameters for those base standards necessary to accomplish a particular function.

property:

A classification of any feature that humans naturally use to distinguish one individual object from another. It is any one of the charactistics of an object class that humans use as a label, quantity, or description. It has no particular associated means of representation by which the property can be communicated.
protocol:

A formal set of conventions governing the format and control of interaction among communicating functional units. In layered communications system architecture, a formal set of procedures that are adopted to facilitate functional interoperation within the layered hierarchy. (FS-1037C)

protocol control information (PCI):

In OSI, information exchanged between entities of a given layer, via the service provided by the next lower layer, to coordinate their joint operation.

protocol data unit (PDU):

In OSI, a set of data specified in a protocol of a given layer and consisting of protocol control information of that layer, and possibly user data of that layer.

qualifier:

A term that helps define and render the name of a concept unique.

registration:

The assignment of an unambiguous identifier to a data element in a way that makes the assignment available to interested parties. (ISO/IEC 11179-6)

registration authority (RA):

Any organization authorized to register data elements. (ISO/IEC 11179-6)

registration status:

A designation of the position in the registration life-cycle of a data element. (ISO/IEC 11179-6)

relationship:

Business-based association between or among entities.

representation:

The part of a data element having a value domain, datatype, and, if a quantity, a unit of quantity.

responsible organization (RO):

The organization or unit within an organization that is responsible for the contents of the mandatory attributes by which the data element is specified. (ISO/IEC 11179-6)

schema:

A description or representation of the structure of data.

service:

In network architecture, the capabilities that a layer provides to the adjacent layer closer to the end user. The service in a given layer may depend upon services in layers closer to the media. (ISO/IEC 2381-18) Rationale: The notion of a layer of the OSI Reference Model providing services and the standards that define those services should be described with the standards for protocols and profiles. Concrete, abstract, and transfer syntax are used by application functions as a means of communication with the services provided by the layers of the OSI Reference Model.

submitting organization (SO):

The organization or unit within an organization that has submitted the data element for addition, change or cancellation/withdrawal in the data element dictionary. (ISO/IEC 11179-6)
transaction:

A command, message, or input record that explicitly or implicitly calls for a processing action, such as updating a file.

value domain:

Restricted permissible values. It provides representation, but has no implication as to what data concept the values are associated nor what the values mean.

The definitions presented above come from a number of sources including a recent draft of the American National Standard Dictionary of Information Technology (ANSDIT). Since ANSDIT is in draft the definitions are subject to change and are only a starting point for refinement as appropriate to the ITS community. The dictionary is based on the American National Standard Dictionary of Information Systems, ANSI X3.172-1990 and its earlier editions and has been harmonized with ISO/IEC-2382, Information Technology - Vocabulary. Alternate sources include ISO/IEC 11179, Specification and Standardization of Data Elements; FS-1037C, Glossary of Telecommunications Terms which may be more appropriate within the ITS context. In other cases terms have been proposed by participants in the IEEE DD-Working Group as well as other groups.

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end; 4 March 97

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