Geoarchiving Glossary

Any jargon can be overwhelming when one is first exposed to it, including those terms and acronyms used in both the archival and GIS profession. This page provides brief definitions of terms that are used both on the GeoMAPP website and in project documentation. As new terms are identified they will be posted to this page. Please email us at geomapp@ncdcr.gov if you have any recommendations to add.

A | C | E | F | G | H | I | L | M | N | O | P | R | S | T | V | W | X


A

Archival Record - materials created or received by a person, family, or organization, public or private, in the conduct of their affairs that are preserved because of the enduring value contained in the information they contain or as evidence of the functions and responsibilities of their creator. Archival records may be in any format, including text on paper or in electronic formats, photographs, motion pictures, videos, sound recordings. (Society of American Archivists [SAA] Glossary)

Archival Value - the ongoing usefulness or significance of records, based on the administrative, legal, fiscal, evidential, or historical information they contain, justifying their continued preservation. In general, records with archival value are estimated to make up only three to five percent of an organization's records. (SAA Glossary)

Attribute Data - generally defined as additional information about each spatial feature housed in tabular format.


C

Checksum - a checksum is calculated from the data using a known formula that returns a single-digit value and is stored with the data. At any point the checksum can be recalculated to see if the value has changed. (SAA Glossary)

Clearinghouse - see Spatial Data Clearinghouse

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E

EAD (Encoded Archival Description) –standard used to mark up (encode) finding aids that reflects the hierarchical nature of archival collections and that provides a structure for describing the whole of a collection, as well as its components. (SAA Glossary)

ESRI (Environmental Systems Research Institute) - providers of GIS Software (such as ArcGIS).)

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F

Feature - natural and man-made geographic features represented by points/symbols, lines, and areas on a map. Object in a geographic or spatial database with a distinct set of characteristics. For example, a road segment, manhole, building, or area designated having the same soil type. (http://www.kansasmappers.org/kam/services/gisdictionary.cfm#P)

FGDb (File Geodatabase) - a native file structure for ArcGIS. It shows as a folder in the Windows file system. Each dataset is held as a file that can scale up to 1 TB in size. It is a folder of binary formats, and is supported on any operating system platform. Preferred to a personal geodatabase. Supports individual datasets containing over 300 million features and that can scale beyond 500 GB. (ESRI definition).

FGDC (Federal Geographic Data Committee) – promotes sharing of the nation’s geospatial resources. The FGDC metadata standard was adopted in 1994, and is a standard developed to determine the robustness, the method of accessing, and the successful transfer of geospatial data. (http://www.fgdc.gov/metadata)

Framework Data - geospatial datasets deemed to be the most critical or commonly used for a wide variety of mapping and analytical purposes. The RAMONA GIS Inventory database delineated 23 datasets as being “framework”.

FTP (File Transfer Protocol) - is used to transfer files between computers on a network, such as the Internet. You can use FTP to exchange files between computer accounts, to transfer files between an account and a desktop computer, or to access software archives on the Internet. Keep in mind, however, that many FTP sites are heavily used and require several attempts before connecting.

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G

Geoarchive – refers to a digital records repository designed to ingest and manage archived geospatial content.

Geodatabase – collection of geographic datasets (features class [a collection of features or a table of rows, where each row has a geographic column], raster data, attribute tables). This is a native structure for ESRI ArcGIS. There are three types of geodatabases: personal geodatabase, file geodatabase, and ArcSDE.

Geographical Information Systems (GIS) – incorporates graphical features with tabular data in order to assess real-world problems (e.g., prioritizing sensitive species habitat to determining optimal real estate locations for new businesses). At the simplest level, GIS can be thought of as a high-tech equivalent of a map. The key word to this technology is Geography – this usually means that the data (or at least some proportion of the data) is spatial, in other words, data that is in some way referenced to locations on the earth. Coupled with this data is usually tabular data known as attribute data. Attribute data is generally defined as additional information about each of the features, which then can be tied to spatial data. (http://gislounge.com/what-is-gis/)

Geospatial Metadata – provides a way to describe geospatial data and other electronic records. It contains such information as the coordinate system, when the data was created, when it was last updated, who created it and how to contact them and definitions for any of the code attribute data.

GIS – see Geographical Information Systems

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H

Hash function - a mathematical algorithm that takes an electronic document and creates a document fingerprint. The document fingerprint is much smaller than the original document, and does not allow the reconstitution of the original document from the fingerprint. A slightly different document, processed through the same hash function, would produce a very different document fingerprint. A hash function helps to secure data by providing a way to ensure that data are not compromised. (http://www.records.ncdcr.gov/guides/AH_Best_Practices_Digital_Preservation_Final_2008_04_01.pdf)

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I

ISO (International Organization for Standardization) 19115 - defines the schema required for describing geographic information and services. It provides information about the identification, the extent, the quality, the spatial and temporal schema, spatial reference, and distribution of digital geographic data. (http://www.iso.org/iso/catalogue_detail.htm?csnumber=26020)

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L

Layer - the visual representation of a geographic dataset in any digital map environment. Conceptually, a layer is a slice or stratum of the geographic reality in a particular area, and is more or less equivalent to a legend item on a paper map. On a road map, for example, roads, national parks, political boundaries, and rivers might be considered different layers. (ESRI Glossary: http://support.esri.com/)

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M

MARC (Machine Readable Cataloging) - data communications format that specifies a data structure for bibliographic description, authority, classification, community information, and holdings data. (SAA Glossary)

Metadata Schema - A metadata schema defines a framework for representing metadata. In general it includes definition of terms used in the schema, structural constraints and data structure definitions, and bindings to physical description syntax. For additional information, see:http://www.ieee-tcdl.org/Bulletin/v3n1/nagamori/nagamori.html.

Metadata Wrapper - In general, a metadata wrapper would contain all additional bits of metadata elements including descriptive, administrative, technical, and structural metadata.

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N

Network - a number of computers connected together to share information and hardware. A Local Area Network (LAN) is small, usually confined to a single building or group of buildings. A Wide Area Network (WAN) is a system of LAN’s. It is large, with many computers linked.

Non-Framework Data - see Framework Data. Any geospatial datasets that are not included in the list of 23 Framework datasets listed above.

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O

OAI-PMH (Open Archives Initiative – Protocol for Metadata Harvesting) – published by OAI, the protocol defines an application-independent interoperability framework based on metadata harvesting. The framework is used by data providers, who expose metadata about information held in a repository, and by service providers, who use that metadata to build value-added services. See http://www.openarchives.org/

Orthoimagery – digital imagery in which distortion from the camera angle and topography have been removed, thus equalizing the distances represented on the image. A rectified copy of a photograph (typically an aerial photograph), showing image features corrected for variations in scale and height displacements. (From http://www.websters-online-dictionary.org/or/orthophotography.html/). Aerial photographs that more precisely show the features of the landscape, including those that might be important for agriculture such as slope or size of gullies, because they are corrected for distortion caused by tilt, curvature, and ground relief.

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P

Permanent Record – see Archival Record.

Projection - a system to portray all or part of the earth, which is an irregular sphere, on a planar or flat surface.

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R

Record - data or information in a fixed form that is created or received in the course of individual or institutional activity and set aside (preserved) as evidence of that activity for future reference. A record has fixed content, structure, and context. (SAA Glossary).

Retention and Disposition Schedule - a document that identifies and describes an organization's records, usually at the series level, provides instructions for the disposition of records throughout their life cycle. (SAA Glossary)

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S

.shp file (“shapefile”) – (from ESRI) stores non-topological geometry and attribute information for the spatial features in a data set (digital vector storage format created in ArcView). The geometry for a feature is stored as a shape comprising a set of vector coordinates. Because shapefiles do not have the processing overhead of a topological data structure, they have advantages over other data sources such as faster drawing speed and edit ability. Shapefiles handle single features that overlap or that are noncontiguous. They also typically require less disk space and are easier to read and write.

Spatial Data - also known as geospatial data or geographic information it is the data or information that identifies the geographic location of features and boundaries on Earth, such as natural or constructed features, oceans, and more. Spatial data is usually stored as coordinates and topology, and is data that can be mapped. Spatial data is often accessed, manipulated or analyzed through Geographic Information Systems (GIS). (http://www.webopedia.com/TERM/S/spatial_data.html).

Spatial data = Spatial (Where) + Data (What)

Spatial Data Clearinghouse – repository structure, physical or virtual, that collects, stores, and disseminates information, metadata, and data. A clearinghouse provides widespread access to information and is generally thought of as reaching or existing outside organizational boundaries. (Wade, T. and Sommer, S. eds. A to Z GIS)

Storage Area Network (SAN) - is a network specifically dedicated to the task of transporting data for storage and retrieval. SAN architectures are alternatives to storing data on disks directly attached to servers or storing data on Network Attached Storage (NAS) devices which are connected through general purpose networks.

SDE (Spatial Database Engine) - refers to ESRI’s spatial database engine. It is a relational database management system that provides a formal structure for storing and managing information in tables. For additional information, see: (http://www.esri.com/software/arcgis/geodatabase/storage-in-an-rdbms.html).

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T

Tabular Data - consists of attribute tables that define the parameters of the map features. There is really no limit to what the tables can contain, whether Boolean strings (True/False), Text, or Numeric data. For example, a Boolean entry in a cities table may define whether or not each city is a national capital. A text entry may have the city's name, or the archaeological period in which it flourished. A numeric entry could have population figures or lat/long coordinates. The advantage of the relational database system is that the different columns can be sorted and selected according to the user's need. These selections then appear highlighted on the map. (http://www.umich.edu/~ipcaa/GIS/General%20GIS%20Concepts.htm).

Temporal – existing for a time only. As an example, in the Dublin Core elements, temporal can be defined by a date, date range or a named period.

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V

Vector Data –spatial data represented as points, lines and polygons. This system of recording features is based on the interaction between arcs and nodes, represented by points, lines, and polygons. A point is a single node, a line is two nodes with an arc between them, and a polygon is a closed group of three or more arcs. With these three elements, it is possible to record most all necessary information. (http://www.umich.edu/~ipcaa/GIS/General%20GIS%20Concepts.htm)

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W

Web Map Service (WMS) – is an Open Geospatial Consortium (OCG) Web service standard for exchanging map information as map images. WMS allows a user to request map images over the web using open standards. WMS supports the use of datasets without the need to keep a local copy.

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X

XML (Extensible Markup Language) - a standard to promote sharing information over the Internet by specifying ways to describe the information's semantic structure and to validate that the structure is well formed. XML is described as extensible because it is a metalanguage that allows the creation of tags to be used for semantic markup. The greatest value of XML can be realized through common vocabularies of tags, so that applications can use those vocabularies to understand documents from different sources.

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Last Modified: 7/5/2011

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