GLOSSARY of ECDIS-RELATED TERMS

Transcription

1 INTERNATIONAL HYDROGRAPHIC ORGANIZATION GLOSSARY of ECDIS-RELATED TERMS 3rd Edition - December 1997 Special Publication No. 52 Appendix 3 Published by the International Hydrographic Bureau MONACO 400-II-1998 S-52 App. 3

2 INTERNATIONAL HYDROGRAPHIC ORGANIZATION GLOSSARY of ECDIS-RELATED TERMS 3rd Edition - December 1997 Special Publication No. 52 Appendix 3 Published by the International Hydrographic Bureau 4, Quai Antoine 1er B.P MC MONACO Cedex Principauté de Monaco Telex: MC- INHORG Telefax: (377) info@ihb.mc Web:

3 i Preface The purpose of this Glossary of ECDIS-related terms is to facilitate reading and interpreting the standards and specifications related to ECDIS issued by IMO and IHO, namely the ECDIS Performance Standards, the IHO Special Publications S-52 (including its Appendices) and S-57. This 3rd edition has been developed by the Glossary Working Group of the IHO Committee on Hydrographic Requirements for Information Systems (CHRIS). It has been completely revised based on the latest editions of the relevant ECDIS-related standards and specifications. The reader should be aware that it is not intended to cover everything that has a bearing on ECDIS, and that many definitions only reflect a rather narrow meaning the terms have in conjunction with ECDIS. The Glossary, therefore, should not be used as general reference for hydrographic, navigational or information technology terms. Some of the relevant IHO specifications contain a glossary of terms on their own. Only those definitions which have a wider use beyond the limits of a particular publication have been incorporated from these specific glossaries. The "invention" of new definitions has been avoided as far as possible. Use has been made instead of either general dictionaries such as the Hydrographic Dictionary (IHO Special Publication S-32), and Bowditch, or of other relevant documents. References are provided in square brackets. It should be noted that sometimes a definition taken from another source may be an excerpt from the original definition, or is slightly modified in order to better meet ECDIS terminology. Where it was felt, however, that the special meaning of a term in conjunction with ECDIS requires a correspondingly specialized approach, new definitions were developed. Advantage has been taken of guidelines provided in the "Short guide for writing definitions" published by the ISO TC211 Committee [ISO]. In particular, an attempt has been made to separate the core of the definition from any additional explanations, examples etc. through the addition of Notes. All entries to the Glossary are given in lower case, except acronyms and proper names. Cross references to other definitions in the Glossary are provided by italicizing the respective term.acronyms are integrated in the Glossary with cross references. Some illustrations are annexed to the Glossary to show relationships between terms. Any suggestions for improvement, corrections and extensions are welcome. As the Working Group will be disbanded on publication of this edition, comments should be addressed to the Chairman of CHRIS through the International Hydrographic Bureau.

4 ii Page intentionally left blank

5 1 accuracy The extent to which a measured or enumerated value agrees with the assumed or accepted value. See precision. [HD] aid to navigation Visual, acoustical or radio device external to a vessel designed to assist in the determination of a safe course or of a vessel's position, or to warn of dangers and obstructions. [Bowditch] AIS See Automatic Identification System. alarm An alarm or alarm system which announces by audible means, or audible and visual means, a condition requiring attention. [PS] all other information Term used in the Performance Standards for ECDIS to describe information not belonging to the standard display. Also sometimes called "on-demand information". (See Fig. 3) application profile Data structure. A defined subject of the S-57. [TS] Note: An application profile is defined for a specific purpose, such as the transfer of ENC data. applier An entity controlling the application of the updateinformation, e.g. the mariner keying in update information, or the software inside ECDIS automatically processing the ENC update information. [UG] area ARPA The 2-dimensional geometric primitive of an object that specifies location. (See Fig. 4) See Automatic Radar Plotting Aid. attribute A characteristic of an object. It is implemented by a defined attribute label/code, acronym, definition and applicable values. In the data structure, the attribute is identified by its label/code. The acronym is only used as a quick reference in related documents and in ENC Product Specification. Attributes are either qualitative or quantitative. [TS] Note: see Appendix A, IHO Object Catalogue. attribute label/code A fixed length numeric label or a 2-byte unsigned integer code of an attribute as defined in Appendix A, IHO Object Catalogue. [TS] attribute value See attribute label/code. Automatic Identification System (AIS) An automatic communication and identification system intended to improve the safety of navigation by assisting in the efficient operation of vessel traffic services (VTS), ship reporting, ship-to-ship and ship-to-shore operations. Note: A transponder is an example of an AIS. AIS information may be displayed on an ECDIS.

6 2 automatic updating Either the semi-automatic or the fully automatic means of updating the ENC/SENC. [UG] Automatic Radar Plotting Aid (ARPA) A system wherein radar targets are automatically acquired and tracked and collision situations computer assessed and warnings given. azimuth The bearing of a geographical position, measured clockwise from north through 360 degrees. [Bowditch] back-up arrangement Facilities enabling safe take-over of the ECDIS functions and measures facilitating means for safe navigation of the remaining part of the voyage in case of an ECDIS failure. [PS] base data S-57 conforming data at the data producer's site that does not contain any update records.once this data is exchanged it becomes target data at the applier's site. [TS] bearing (BRG) The direction from a reference station, usually from 000 degrees at the reference direction, clockwise through 360 degrees. [Bowditch] block correction see chartlet. cartographic object Feature object which contains information about the cartographic representation (including text of real world entities. [TS] Note: The ENC Product Specification prohibits the use of cartographic objects in ENCs. cautionary note Information calling special attention to some fact, usually a danger area shown on a chart, or other publication. [HD] cell chain The basic unit for the distribution of ENC data covering a defined geographical area bounded by two meridians and two parallels, the content of which must not exceed 5 Mbytes, and which is intended for a particular navigational purpose. A sequence of one or more edges. chain node Data structure in which the geometry is described in terms of edges, isolated nodes and connected nodes. Edges and connected nodes are topologically linked. Nodes are explicitly coded in the data structure (see Fig. 5). [TS] Note: Spatial objects may be shared between feature objects. Where spatial objects are shared, lines that cross are broken (into edges) at the intersection and a logical node is implied (ie nodes are not explicitly created, the geometry of the node remains part of the edge). Where spatial objects are not shared, lines may cross without being broken at the intersection. Areas are defined by the sequence of edges that comprise their boundaries. Lines are comprised of edges. Point feature objects may only reference isolated nodes.

7 3 chart amendment patch see chartlet. chart cell see cell. chart information HO-information relevant to navigation contained in nautical charts. (SeeFig.2) chart datum A permanently established surface from which soundings or tide heights are referenced. Short for chart sounding datum. [HD] Note: A plane so low that the tide will not frequently fall below it. [TR] chart A chart specifically designed to meet the requirements of marine navigation, showing depths of water, nature of bottom, elevations, configuration and characteristics of coast, dangers and aids to navigation. [HD] Note: The carriage of up-to-date charts (plus certain other nautical publications) by vessels at sea is a mandatory requirement of SOLAS regulation V 20. The term nautical chart may be applied also to a specially compiled data base (e.g., the ENC), from which such a map can be displayed. chart symbol A character, letter, line style, or similar graphic representation used on a chart to indicate some object, characteristic, etc. [HD] chartwork All navigational procedures carried out on a chart, the elements and parameters of which are listed in Annex 3 of the ECDIS Performance Standards. CHRIS See Committee on Hydrographic Requirements for Information Systems. C.I.E. colour system Colour specification system established by the Commission Internationale de l'eclairage, which permits a replicable description of any colour on any equipment; in contrast with other colour schemes, which are apparatus specific. Colour is usually expressed in terms of the x and y chromaticity coordinates for the widely used chromaticity diagram, and a third dimension Y representing the luminance (perceived as brightness) of the light in candela per square metre (cd/m 2 ). C.I.E. colour coordinates can be transformed into RGB coordinates of a calibrated CRT. clarifications section One of the mechanisms used to maintain S-57. Seemaintenance document. clutter Excess information or noise data on a display reducing its readability. Note: E.g., information overload on a chart, or confusing unwanted wave echoes on a radar display. [HD] coastal warning A navigational warning promulgated by a national co-ordinator covering a coastal region or a portion thereof.

8 4 collection object A feature object which describes the relationship between other objects. [TS] Note: An example of a collection object in S-57 is "aggregation" which is used, for example, to group together the different objects which together constitute a Traffic Separation Scheme. colour calibration In order to reproduce the IHO colours for ECDIS, a colour calibration at the monitor must be performed to transform the CIE-specified colours for ECDIS into the colour coordinate system of the screen. Calibration will ensure correct colour transfer at the time a display leaves the manufacturer's plant. Methods of colour maintenance under operational use are under investigation. Note: colour calibration is described in Appendix 2 of IHO S-52. colour differentiation test diagrams Screen diagrams supplied in the Presentation Library for use by the mariner to check brightness and contrast settings and to find out whether the screen still has the capability of distinguishing the important colours. colour fill Method of distinguishing different area features by filling areas with colour. "Transparent" colour fill is used to allow information to show through the fill, e.g., soundings in a traffic separation zone. colour tables Five colour tables are supplied in IHO S-52 Appendix 2, for selection by the mariner. They are bright sun, day white-background, day black-background, dusk and night. colours for ECDIS The colours specified by the IHO for ECDIS have been developed by Perception Institutes to give a clear display through the optimum colour contrast under all viewing conditions, and to minimise light emission on the darkened bridge at night. Colours are used to aid in distinguishing between features. Colours for ECDIS are specified in the CIE colour system. Committee on ECDIS (COE) Committee of the IHO responsible for ECDIS matters until Now replaced by the Committee on Hydrographic Requirements for Information Systems (CHRIS). Committee on Exchange of Digital Data (CEDD) Committee of the IHO responsible for the Transfer Standard for Digital Hydrographic Data until Now replaced by the Committee on Hydrographic Requirements for Information Systems (CHRIS). Committee on Hydrographic Requirements for Information Systems (CHRIS) A Committee of the IHO tasked with promoting and coordinating the development of official digital products and services. compilation In cartography, the selection, assembly, and graphic presentation of all relevant information required for the preparation of a new map/chart or a new edition thereof. Such information may be derived from other maps/charts, aerial photographs, surveys, new data, and other sources. compilation scale The scale at which the ENC data was compiled.

9 5 compilation update The correction information which has been issued since the last new edition of the ENCor since the last official update applied to the SENC, compiled into a single, comprehensive ENC update. [UG] Note: Example: if a buoy has been relocated two or more times since the ENC Edition, only the last position, tailored to correct the position contained in the ENC Edition as issued, would be included. Thus, the application of a compilation update is to correct the effective ENC Edition at the time of its distribution to a user, which could be some months or years after the Edition's initial distribution. Compilation update is implemented in S-57 by means of a re-issue of an ENC. conditional symbology procedure A decision-making procedure used to link an object-class to a symbol in cases where the symbol depends on circumstances (e.g. whether a wreck is symbolised as an "isolated danger" depends on its relationship to the safety contour chosen by the mariner), or where symbolisation is complex (e.g. light sectors). connected node A node referred to as a beginning and/or end node by one or more edge. Connected nodes are defined only in the chain-node, planar graph and full topology data structures. [TS] correction information See update information. corrections See update information. corrections section One of the mechanisms used to maintain S-57. Seemaintenance document. corrupted data Any change in data introduced during, and as a result of, its transmission. [UG] course The horizontal direction in which a vessel is intended to be steered, expressed as an angular distance from north clockwise through 360 degrees. [Bowditch] course made good (CMG) The single resultant direction from a vessel's point of departure to its point of arrival at any given time. [Bowditch] Note: Relates to each leg of the track. course over ground (COG) The direction of a vessel's path actually followed, usually a somewhat irregular line. [Bowditch] course up display The information is shown on the display (radar or ECDIS) with the direction of the vessel's course upward. The display orientation is stabilized by means of the gyro until a new course direction is fed in. Note: Course-up orientation avoids the disadvantages with the head-up display due to yawingor other changes in heading. cumulative update The collection of all sequential correction information which has been issued since the last new edition of the ENC or since the last official update applied to the SENC. [UG]

10 6 cursor-pick The process of querying a point-symbol, line or area for further information from the data base which is not represented by the symbol. data dictionary Conveys the meaning of entities and attributes,the relationship between entities and attributes and the relationship between attribute and value domains. data model A conceptual specification of the sets of components and the relationships among the components pertaining to the specific phenomena defined by the model reality. A data model is independent of specific systems or data structures. The S-57 data model defines real world entities as a combination of descriptive and spatial characteristics. These characteristics are defined in terms of feature objects and spatial objects and the relationship between them. See Fig. 4. data quality indicator Indication of reliability and accuracy of surveys of a particular area provided through CATZOC attribute of the quality of data meta object in S-57. data set A logical grouping of S-57 data to which the S-57 data set descriptive records apply. The data set descriptive records contain meta data. The use of data set descriptive records is product specific and is, therefore, defined by a product specification. If the data set descriptive records are repeated for each file in an exchange set, an instance of a file containing the data set descriptive records is called a data set. If the data set descriptive records are encoded generally for the whole exchange set, the exchange set is referred to as a data set. [TS] data structure A computer interpretable format used for storing, accessing, transferring and archiving data. [ISO] datum (geodetic) A set of parameters specifying the reference surface or the reference coordinate system used for geodetic control in the calculation of coordinates of points on the earth. Commonly datums are defined as horizontal and vertical datums separately. For a local geodetic datum the reference surface is defined by five parameters: the latitude and longitude of an initial point, the azimuth of a line from this point, and the parameters of the reference spheroid. Absolute datums specify the initial point of the reference ellipsoid to be (ideally) located at the earth's centre of mass. For modern reference systems using datum information given by satellites additional parameters are defined, e.g. gravity models. [HD] datum (vertical) Any level surface (e.g. sea mean sea level) taken as a surface of reference from which to reckon elevations. [HD] Note: See also chart datum. degradation The deterioration in the performance of a system below a specified minimum level. Note: For example, the reduction in the information content of a display, a data base or other means of providing information below an acceptable or agreed level. [IEC] Differential GLONASS (DGLONASS) see GLONASS

11 7 Differential GPS (DGPS) see GPS Differential System An augmentation system whereby radionavigation signals are monitored at a known position and the corrections so determined are transmitted to users in the coverage area. [GNSS] digital terrain model (DTM) A model representing the terrain surface by a collection of digital data, mainly coordinates in three dimensions, x, y, and z, and a digitally defined method to interpolate arbitrary terrain heights in between the stored values. [HD] Note: Not to be confused with digital cartographic model which may also contain digital data representing terrain, but in a form suitable for the drawing of a particular kind of map. digitizing conventions see encoding conventions display A visual presentation of data. Note:For example, a presentation of a line of alphanumeric data, a window or the entire screen. display base see display category display category The ECDIS Performance Standards establish three categories for SENC objects: display base: permanently retained on the display. standard display: displayed at switch-on, recalled by single operator action. all other information: displayed individually (by class) on demand. The category of every object is given in the look-up table. See Fig. 2, 3. display generator Software written by the ECDIS manufacturer to take an object from the SENC, assign a symbol and colour to it, and present it appropriately on the display, using the tools and procedures provided in the Presentation Library. display priority Detailed rules to decide which line or point symbol is to be shown when two objects overlap. Priority 2 overwrites 1. Display priority is given in the look-up table. display priority for radar Radar is normally written over most chart areas and under most lines and point symbols; the detailed priorities are given in the look-up table. display priority layer Layers to establish the priority of information on the display. Information of lower priority must not obscure higher priority information. display scale The ratio between a distance on the display and a distance on the ground, normalised and expressed as for example 1/10,000 or 1:10,000. drawing sequence The implementation of display priority.

12 8 Note:Specifies, within a display priority layer, which of two overlapping objects is drawn on top of the other. DX90-format The name given to the data structure in S-57 versions 1 and 2. It is not used in S-57 edition 3. ECDIS Chart 1 An ECDIS version of IHO INT1, including all symbols, linestyles and colour coding used for chart and navigation symbols, contained in the Presentation Library. edge A one-dimensional spatial object, located by two or more coordinate pairs (or two connected nodes) and optional interpolation parameters. If the parameters are missing, the interpolation is defaulted to straight line segments between the coordinate pairs. In the chain-node, planar graph and full topology data structures, an edge must reference a connected node at both ends and must not reference any other nodes. [TS] electronic chart Very broad term to describe the data, the software, and the electronic system, capable of displaying chart information. An electronic chart may or may not be equivalent to the paper chart required by SOLAS. Electronic Chart Data Base (ECDB) The master data base for Electronic Navigational Chart Data (ENCD), held in digital form by the national hydrographic authority, containing chart information and other nautical and hydrographic information. (See Fig. 1). [UG] Electronic Chart Display and Information System (ECDIS) A navigation information system which with adequate back-up arrangements can be accepted as complying with the up-to-date chart required by regulation V/20 of the 1974 SOLAS Convention, by displaying selected information from a System Electronic Navigational Chart (SENC) with positional information from navigation sensors to assist the mariner in route planning and route monitoring, and if required display additional navigation-related information. [PS] Electronic Chart Systems (ECS) Generic term for equipment which displays chart data but which is not intended to comply with the IMO Performance Standards for ECDIS, and is not intended to satisfy the SOLAS Chapter V requirement to carry a navigational chart. Electronic Navigational Chart (ENC) The data base, standardized as to content, structure and format, issued for use with ECDIS on the authority of government authorized hydrographic offices. The ENC contains all the chart information necessary for safe navigation and may contain supplementary information in addition to that contained in the paper chart (eg sailing directions) which may be considered necessary for safe navigation. (See Fig. 1, 2). [PS] Electronic Navigational Chart Data (ENCD) The national data for an Electronic Navigational Chart (ENC) in a format acceptable to an ENC Coordinator. (See Fig. 1). [UG] Note: The content, structure and format of the ENC are specified in IHO S-57 edition 3 and the associated ENC product specification [IEC].

13 9 Electronic Navigational Chart Data Base (ENCDB) The master data base for production and maintenance of the ENC, compiled from national ENC data (ENCD). (See Fig. 1). [UG] ENC See Electronic Navigational Chart. ENC cell structure See cell. ENC data See Electronic Navigational Chart Data (ENCD). ENC Product Specification Appendix B1 of S-57 which specifies the content, structure and other mandatory aspects of an ENC. ENC test data set A standardized data set supplied on behalf of the International Hydrographic Organization (IHO) that is necessary to accomplish all IEC testing requirements for ECDIS. This data set is encoded according to the IHO S-57 ENC product specification and contains update information based on IHO S-52 Appendix 1. The specific requirements are listed in Annex F of IEC encapsulation The identification of fields and records and the groupingof fields and records and the data syntax rules used. encoding conventions A set of rules which must be followed when encoding data for a particular purpose. Note: For example, S-57 Appendix B1 lists the encoding conventions to be used when encoding ENC data, such as the rules to be followed when encoding depth areas. Sometimes referred to as digitizing conventions. Enhanced Group Call (EGC) A global automatic service by INMARSAT for addressing commercial messages (FleetNet) or Maritime Safety Information (MSI) (SafetyNet) to groups or ships or all vessels in both fixed and variable geographical areas. Data transmission is based on INMARSAT Standard-C and takes place at an effective transmission rate of 600 bit/s. [UG] entity Any concrete or abstract thing of interest, including associations of things. [ISO] exchange format A specification for the structure and organization of data to facilitate exchange between computer systems. exchange set The set of files representing a complete, single purpose (i.e. product specific) data transfer. The ENC Product Specification defines an exchange set which contains one Catalogue file and at least one data set file. [TS]

14 10 extensions document One of the three documents used to maintain S-57. It contains extensions, or other significant changes to the Standard, which have been agreed by the appropriate IHO committee or working group, and will be included in the next edition of the Standard. See also clarifications document, corrections document. Note: Available from IHB only on demand. [TS] face A two dimensional spatial object. A face is a continuous area defined by a loop of one or more edges which bound it. A face may contain interior holes, defined by closing loops of edges. These interior boundaries must be within the outer boundary. No boundary may cross itself or touch itself other than at the beginning/end node. None of the boundaries may touch or cross any other boundary. Faces are defined only in the full topology data structure. [TS] feature Representation of a real world phenomenon. [ISO] Note: For example, a particular cardinal buoy represented through a symbol on a chart. feature object An object which contains the non-locational information about real world entities. Feature objects are defined in Appendix A, IHO Object Catalogue. See also geo, meta, collection and cartographic objects. See Fig. 4. [TS]. feature record A feature record is the implemented term used in the S-57 data structure for a feature object (i.e. a feature object as defined in the data model is encoded as a feature record in the data structure). There are four types of feature records: geo, meta, collection and cartographic. [TS] field file A named collection of labelled subfield(s). For example, IHO attribute label/code and IHO attribute value are collected into a field named Feature Record Attribute. An identified set of S-57 records collected together for a specific purpose. The file content and structure must be defined by a product specification. [TS] fully automatic updating The application of corrections to ENC data in the SENC in a fully integrated state, without human intervention at the receiving end. [UG] full topology A 2-dimensional data structure in which the geometry is described in terms of nodes, edges and faces which are all topologically linked. A planar graph with faces. [TS] generalization The omission of less important detail when compiling a chart. Its purpose is to avoid overloading charts where space is limited. [HD] geo object A feature object which carries the descriptive characteristics of a real world entity. [TS] Note: The positional information is provided through the spatial object.

15 11 Geographic Information System (GIS) A computer based system for handling and integrating data from a variety of sources which is directly or indirectly spatially referenced to Earth. [HD] geometric primitive One of the three basic geometric units of representation: point, line and area. (See Fig. 4). [TS] Global Maritime Distress and Safety System (GMDSS) A global communications service based upon automated systems, both satellite based and terrestrial, to provide distress alerting and promulgation of maritime safety information to mariners. [HD] Note: This system has been developed by IMO through the SOLAS Convention. Global Navigation Satellite System (GNSS) A world-wide position, time and velocity radiodetermination system comprising space, ground and user segments of which GPS and GLONASS are components. [GNSS] GLONASS (Global Navigation Satellite System) A space-based, radio-positioning, navigation and time-transfer system operated by the Government of the Russian Federation. GLONASS to which differential corrections have been applied is known as Differential GLONASS (DGLONASS). GPS (Global Positioning System) A space-based, radio-positioning, navigation and time-transfer system operated by the United States Government. GPS to which differential corrections have been applied is known as Differential GPS (DGPS). ground stabilization A display whereby own ship position is referenced to the ground. Usually performed in conjunction with radar/arpa, it can be determined by computing set and drift or by the use of GPS/differential GPS. Harmonization Group on ECDIS (HGE) Joint Working Group of IMO and IHO tasked with maintaining the ECDIS Performance Standards and addressing other related issues. heading (HDG) The direction in which a vessel is pointed, expressed as an angular distance from north clockwise through 360 degrees. A constantly changing value as a vessel yaws back and forth across the course due to the effects of sea, wind, etc. [Bowditch] head-up display The information shown on the display (radar or ECDIS) is directed so that the vessel's heading is always pointing upward. This orientation corresponds to the visual view from the bridge in direction of the ship's heading. This orientation may require frequent rotations of the display contents. Changing the ship's course, or yawing of the vessel may render this unstabilized orientation mode unreadable (See course-up display). HO-information Information content of the SENC originated by hydrographic offices. It consists of the ENC content and updates to it. (See Fig.2) identifier See object identifier.

16 12 IEC See International Electrotechnical Commission. IHO INT 1 Specification of symbols, abbreviations and terms to be used in the International Chart Series of IHO. IHO Transfer Standard for Digital Hydrographic Data Originally published as SP57 (later S-57) Version 1 and then Version 2. The latest release of the standard, S-57 Edition 3, consists of a Theoretical Data Model, Data Structure, Object Catalogue, ENC Product Specification, Use of the Object Catalogue for ENC and an Object Catalogue Data Dictionary Product Specification. IHO test data set See ENC test data set. indication See indicator. indicator Visual indication giving information about the condition of a system or equipment. [PS] information from other sources Information contained within SENC not originating from HO's or the mariner. Note: E.g., manufacturer's chart data of areas where no HO-information is available. (See Fig. 2, 3) INMARSAT International Maritime Satellite Organization, an international worldwide satellite communications links to ships at sea. consortium which provides INT 1 See IHO INT 1. International Electrotechnical Commission (IEC) A worldwide non-governmental organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote international cooperation on all questions concerning standardization in the electrical and electronic fields. [IEC] Note: Committee 80, Working Group 7 of IEC is responsible for developing the Performance Requirements for ECDIS to be published as document IEC International Hydrographic Organization (IHO) Coordinates the activities of national hydrographic offices; promotes standards and provides advice to developing countries in the fields of hydrographic surveying and production of nautical charts and publications. [HD] International Maritime Organization (IMO) The specialized agency of the United Nations responsible for measures to improve the safety of international shipping and to prevent marine pollution from ships [IMO]. ISO 8211 ISO standard on "Information processing -Specification for a data descriptive file for information interchange". This international standard specifies an interchange mechanism to facilitate the

17 13 transfer of files containing data records between computer systems. It defines a generalized structure which can be used to transmit, between systems, records containing a wide variety of data types and structures. It provides the means for the description of the contents of data records but does not define the contents. ISO This ISO standard specifies the Universal Multiple-Octet Coded Character Set (UCS). It is applicable to the representation, transmission, interchange, processing, storage, input and presentation of the written form of the languages (scripts) of the world as well as additional symbols. Note:used to represent certain national language character sets, for example Arabic and Chinese, in S-57. isolated node An isolated zero-dimensional spatial object that represents the geometric location of a point feature. An isolated node is never used as a beginning or end node. [TS] Issuing Authority The official agency which issues the ENC and ENC updates. [UG] See Regional ENC Coordinating Centre. key An identifier which establishes linkages, e.g. between different layers, or features and attributes. label/code See attribute label/code. layer leg line A group of related information displayed as a whole. A line connecting two waypoints. The one-dimensional geometric primitive of an object that specifies location. (See Fig. 4) List of Lights A publication tabulating navigational lights, with their locations, candle powers, characteristics, etc. to assist in their identification, and details of any accompanying fog signal. A list of lights may contain other information useful to a navigator. Also called light list. [HD] Note: This publication is issued under the authority of a marine administration. List of Radio Signals A publication tabulating and combining particulars of: coast radio stations, port radio stations, radio direction finding stations, radiobeacons, etc., as well as other information on radio services useful to a navigator. [HD] Note: This publication is issued under the authority of a marine administration. local datum Any geodetic datum defined for national purposes other than WGS84 which is adopted for use with ECDIS.

18 14 local updates A generic term to indicate all update information other than official updates, regardless of source; for application as a manual update only. [UG] log file A record of updates, including time of application and identification parameters described in Appendix 1 of S-52. [IEC] look-up table A table giving symbology instructions to link SENC objects to point, line or area symbolisation, and providing display priority, radar priority, IMO category and optional viewing group. maintenance document S-57 (apart from Annex A of Appendix B1: "Use of the Object Catalogue") is maintained by means of numbered Maintenance Documents which are produced following each meeting of the Transfer Standard Maintenance and Application Development Working Group (TSMAD). These documents are distributed with the Standard and their contents are also available on the IHB's Bulletin Board System and on the IHO Web site. Each Maintenance Document contains the following three sections: Clarifications. This section contains improvements to the wording of the Standard. These are editorial amendments which do not result in any substantive change to the Standard. Corrections. This section contains substantive changes to the Standard to correct factual errors or amend the contents of the Standard. These changes will be only included in the next edition (Ed 4.0) of the Standard. Extensions. This section contains extensions, or other significant changes to the Standard, which have been agreed by the appropriate IHO committee or working group and will be included in the next edition (Ed 4.0) of the Standard. manual updating The manual application of corrections to ENC data in the SENC by a human operator, usually based on unformatted update information (such as printed NtMs, voice radio, verbal communication etc.). [UG] Note: In order for the SENC to accept manual updates, the update information must be entered in a structured way at least compatible with the relevant ECDIS standards. mariner's information Information originated by and entered by the mariner to the SENC, e.g. area of strong currents. (See Fig. 2, 3) mariner's navigational objects Features, other than chart objects, such as the ownship symbol and velocity vector, planned route, electronic bearing lines, etc from Appendix 3 of the Performance Standards for ECDIS, which are specified in IEC document Maritime Safety Information (MSI) Navigational and meteorological warnings, meteorological forecasts, distress alerts and other urgent safety related messages broadcast to ships. [HD] Note: ECDIS update information is considered MSI.

19 15 matrix An array of regularly spaced locations. [TS] Note: For future use. meta object A feature object which contains information about other objects. [TS] Note: For example compilation scale or vertical datum. nautical chart See chart. Navarea A geographical sea area established for the purpose of co-ordinating the transmission of radio navigational warnings. Navarea warning A navigational warning issued by the Navarea co-ordinator for the Navarea. navigational aid An instrument, device, chart, method, etc., used onboard intended to assist in the navigation of a vessel. [HD] navigational chart Same as nautical chart (in the context of ECDIS). navigational information The information contained in mariner's navigational objects. navigational purpose The specific purpose for which a chart cell has been compiled. There are six such purposes, namely berthing, harbour, approach, coastal, general and overview. navigational symbol see non-chart symbol. navigational warning A broadcast message containing urgent information relevant to safe navigation. Note: See local updates, Navarea warning. Navtex Narrow-band direct-printing telegraphy system for transmission of navigational and meteorological warnings and urgent information to ships. node A zero-dimensional spatial object, located by a coordinate pair. A node is either isolated or connected. (See Fig. 4) [TS] non-chart symbol A symbol for information such as own ship's position, course made good, etc., which appears on the ECDIS but which does not appear on the printed chart. See Mariners Navigational Objects. non-ho information Information contained in the SENC provided bynon-hosources (mariner's information or other sources outside HOs). (See Fig. 2, 3)

20 16 north-up display Information shown on the display (radar or ECDIS) with the north direction upward. Note: The north-up display corresponds with the usual orientation of the nautical chart. Notice to Mariners (NtM) A periodical notice issued by maritime administrations, or other competent authorities, regarding changes in aids to navigation, dangers to navigation, important new soundings, and, in general, all such information as affects nautical charts, sailing directions, light lists and other nautical publications. [HD] NtM object See Notice to Mariners. An identifiable set of information. An object may have attributes and may be related to other objects. Also see spatial object and feature object. [TS] Object Catalogue The Object Catalogue is the feature schema for S-57. Its primary function is to provide a description of real world entities. It contains a list of feature object classes (each relating to a real world entity), attributes and allowable attribute values. object class A generic description of objects which have the same characteristics. Note: Examples of object classes in S-57 are "buoy, cardinal" and "caution area". object description The definition of which object class a specific object belongs to. object identifier The identification of a S-57 feature object. The object identifier is the concatenation of the "Producing Agency", "Feature Identification Number" and "Feature Identification Subdivision" subfields. Within the context of this Standard the object identifier is referred to as the "Long Name". [TS] Note: This provides a unique world-wide identifier for any object as specified in Para 3.1 of the ENC Product Specification. official HO data See HO information. official updates Updates provided in digital format by the Issuing Authority of the ENC being corrected, for integration with the ENC data in the SENC. [UG] on-demand information TheSENC information which is not part of the standard display. See also: All other information. SeeFig.2,3. orientation The mode in which information on the ECDIS is being presented. Typical modes include: north-up. - as shown on a nautical chart, north is at the top of the display. ship's head-up. - based on the actual heading of the ship (e.g. ship's gyrocompass). course-up display. - based on the course or route being taken.

21 17 other chart information See display category and Fig 3. other navigational information Navigational information not contained in the SENC, that may be displayed by an ECDIS, such as radar information. (See Fig. 2) overscale To display the chart information at a display scale larger than the compilation scale. Overscaling may arise from a deliberate overscaling by the mariner, or from automatic overscaling by ECDIS in compiling a display when the data included is of various navigational purposes. Note: An indication is provided only for the partial overscale area of the display. overscale area When the data displayed is from data of two different navigational purposes the chart display will, where drawn at the larger scale, include an overscale area of data from the smaller scale cell in order to complete the display. This area should be identified by the "overscale pattern" of the Presentation Library. Note: E.g., when sailing across the junction between a harbour chart and an approach chart. own ship's safety contour The contour related to the own ship selected by the mariner from the contours provided for in the SENC, to be used by ECDIS to distinguish on the display between the safe and the unsafe water, and for generating anti-grounding alarms. own ship's symbol A non-chart symbol used in ARPA and ECDIS to show the ship's position on the chart or ARPA display. own-ship The term which identifies the vessel upon which an ECDIS is operating. Performance Standards for ECDIS Minimum performance requirements for ECDIS, adopted by IMO 23 November 1995 as Assembly resolution and published as Annex to IMO Resolution A19/Res 817 (15 December 1995). pixel Contraction for "picture element". The smallest element resolvable by electronic raster devices such as scanner, display, and plotter. [HD] planar graph A 2-dimensional data structure in which the geometry is described in terms of nodes and edges which are topologically linked. A special case of a chain-node data structure in which edges must not cross. Connected nodes are formed at all points where edges meet. (See Fig. 5) [TS] point The 0-dimensional geometric primitive of an object that specifies location. (See Fig. 4) polygon A non-selfintersecting, closed chain defining the boundary of an area. [HD]

22 18 product specification A defined subset of the entire specification combined with rules, tailored to the intended usage of the transfer data. See ENC product specification. [TS] precision The degree of refinement of a value. Not to be confused with accuracy. [HD] presentation Cartographic design including drawing, use of symbols, use of colours, use of conventional practices, etc. Presentation Library A set of mostly digital specifications, composed of symbol libraries, colour schemes, look-up tables and rules, linking every object class and attribute of the SENC to the appropriate presentation of the ECDIS display. Published by IHO as Appendix 2 of S-52. raster A regular array with information pertaining to each element (pixel) or group of elements. [TS] raster data presentation Method of representing all, or part, of a chart digitally by a matrix-like scheme of pixels. [HD] record A S-57 construct which is comprised of one or more tagged S-57 fields and identified by a key. [TS] Regional ENC Coordinating Centre (RENC) In the Worldwide Electronic Navigational Chart Data Base (WEND) the IHO network of Hydrographic Offices, the regional node being responsible, as Issuing Authority, for official ENCs and official updates compiled from national ENC data. relationship A logical link between two elements from the data model which may be spatial (e.g. topological relationship) and/or non-spatial. In general a relationship is implemented in the data structure as a pointer. Note: The relationships permitted in ENC data are described in the ENC Product Specification. [TS] relative motion display A display in which own ship remains stationary, while all other charted information and targets move relative to own ship's position. See also true motion display. RENC See Regional ENC Coordinating Centre. resolution Capability of depicting detail, represented by the smallest distance apart at which two objects can be seen to be separate. Depends on pixel size, i.e. screen dimension divided by number of pixels. route A sequence of waypoints and legs.

23 19 route monitoring The operational navigational ECDIS function in which the chart information is displayed, under control of the positioning sensor input, according to the vessel's present position (either in true motion or relative motion display mode). route planning The pre-determination of course, speed, waypoints and radius in relation to the waters to be navigated, and in relation to other relevant information and conditions. [NAV] Note: See also leg, route, voyage plan, waypoint. S-52 S-57 IHO Special Publication 52, titled "Specifications for chart content and display aspects of ECDIS". Additional specifications and guidance are developed in the Appendices of S-52. IHO Special Publication 57. See IHO Transfer Standard for Digital Hydrographic Data. safety contour See Own Ship's Safety Contour. safety depth The depth defined by the mariner, e.g. the ship's draft plus underkeel clearance, to be used by the ECDIS to emphasize soundings on the display equal to or less than this value. Safetynet A service provided through INMARSAT's Enhanced Group Calls (EGC) system which will be used by Administrations for the promulgation of Maritime Safety Information,suchasNavarea and storm warnings, shore-to-ship distress alerts and routine weather forecasts to the high seas and those coastal waters not served by Navtex. IHO proposes to include promulgation of electronic chart corrections as well. [UG] sailing directions A publication issued under the authority of a marine administration providing general coastal navigation information such as aids to navigation, harbour approaches and facilities, and other details necessary which it may not be feasible to show on the corresponding nautical charts. Note: Sometimes referred to as Coastal Pilots or Coast Pilots. scale The ratio between the linear dimensions of a chart, map, drawing, etc., and the actual dimensions represented. [HD] scale bar A vertical bar scale of 1 nautical mile divided into 1/10 ths., intended to convey an immediate sense of distance. Replaced at display scales smaller than 1/80,000 by a 5-mile latitude scale. screen The face of a CRT or other graphic device used to display information from a computer. semi-automatic updating The application of corrections to ENC data in the SENC Updating in a fully integrated state, by hard media or telecommunications transfer in a manner which requires human intervention at the ECDIS interface.

24 20 SENC See Systems Electronic Navigational Chart. simplified symbols Symbols designed specifically for ECDIS, for fast draw and to give the maximum clarity under all conditions of viewing the CRT. They are less complex than the equivalent paper chart symbols. Note: For example, the simplified buoy and beacon symbols are solid, colour-filled symbols designed to show up better at night or in bright sun conditions than the true-to-shape paper chart symbols. The mariner can choose paper chart or simplified symbol sets. SOLAS International Convention for the Safety of Life at Sea developed by IMO. The contracting governments undertake to promulgate all laws, decrees, orders and regulations and to take all other steps which may be necessary to give the present Convention full and complete effect, so as to ensure that, from the point of view of safety of life, a ship is fit for the service for which it is intended [SOLAS]. sounding datum Same as chart datum (for the purposes of ECDIS). spaghetti data A data structure in which all lines and points are unrelated to each other (i.e. no topological relationships exist in the data structure). [TS] Note: This data structure is not permitted for ENC. spatial object An object which contains locational information about real world entities. See Fig. 4. [TS] Note: for example, in S-57 the location of a buoy or the boundary of a caution area. spatial record A spatial record is the implemented term used in the S-57 data structure for a spatial object (i.e. a spatial object as defined in the data model is encoded as a spatial record in the data structure). There are three types of spatial records: vector, raster and matrix. [TS] speed In general, the rate of motion or distance per unit of time. When used in conjunction with ECDIS, speed could be either: [Bowditch] speed of advance (SOA) - speed intended to be made along the track speed over ground (SOG) - the speed along the path actually followed speed made good (SMG) - the speed along the course made good. standard display See display category supplementary information Non-chart HO information, such as sailing directions, tide tables, light list. (SeeFig.2,3) symbol see chart symbol. System Electronic Navigational Chart (SENC) A data base resulting from the transformation of the ENC by ECDIS for appropriate use, updates to the ENC by appropriate means and other data added by the mariner. It is this data base that is actually accessed by ECDIS for the display generation and other navigational functions, and is