Geo4LibCamp Glossary

Here are definitions for terms, acronyms, and jargon commonly used during Geo4LibCamp.


This term is used broadly to describe adding new items to a collection. It is most commonly used in archives and museum terminology, particularly for assigning "accession" numbers to denote when/from where an item was obtained. Digital accessioning can include the concept of a re-accession, for when digital items have been updated or corrected in some way and need to be processed again.


Application Programming Interface. Broadly defined, an API is how different software applications can talk to each other and share information. In library practice, this usually takes the format of a JSON file URL that can be accessed by a script for harvesting data, metadata, or schema information.

ArcGIS Metadata

The current proprietary format used by ArcGIS. It contains all elements required for either FGDC or ISO (as well as other profiles). It also contains technical information specific to the ArcGIS environment, such as thumbnails. Also referred to as ArcGIS 10 metadata.

ArcGIS Dynamic Map Layer

REST service that represents vector data (points, lines, and polygons). Map image layers are dynamically rendered image tiles.

ArcGIS Feature Layer

REST service that displays vector data (points, lines, and polygons) as individual or collected features.

ArcGIS HUB (Open Data Portals)

A portal that uses the ArcGIS Online platform to allow users to organize and publish their data. This platform is very popular with state and local government.

ArcGIS Image Map Layer

REST service that displays raster data (a grid of cells used to store imagery).

ArcGIS Tiled Map Layer

REST service that displays set of web-accessible tiles that reside on a server.


Short for ESRI ArcInfo Grid or Esri Grid. A raster format expressed as a binary or ASCII grid.

Attribute Table

A tabular file or database of the information associated with features or cells in a spatial dataset.


Blacklight is an open source discovery platform framework on which GeoBlacklight is based. It is a customizable Ruby on Rails Engine which provides a basic interface (search box, facet constraints, etc.) for searching an Apache Solr index. Heterogenous data discovery is supported, but not geospatial.

Bounding box

A bounding box delineates the geographic extent of a given spatial dataset, and is typically concieved as the smallest hypothetical rectangle that would fully enclose the features of a spatial dataset. It is defined by four coordinates: the hypothetical rectangle's minimum longitude, minimum latitude, maximum longitude, and maximum latitude. These coordinates correspond, respectively, with the hypothetical rectangle's leftmost line, its bottom, its rightmost line, and its top. A dataset's bounding box is an important component of geospatial metadata. Note that it is often also referred to as an envelope.

CKAN (Comprehensive Knowledge Archive Network)

An open source data platform that can be used for geospatial data.

Cloud Optimized GeoTiffs

A regular GeoTIFF that is internally organized so that it can be hosted and accessed on a HTTP server, meaning users can work with specific portions of images they request

Controlled vocabulary and authorities

Controlled vocabularies are standardized and organized arrangements of words and phrases and provide a consistent way to describe data. Metadata creators assign terms from vocabularies to improve information retrieval. Geospatial controlled vocabulary example: ISO 19115 Topic Categories

Authority records are a type of controlled vocabulary that exist in an index (called an authority file) for the purpose of controlling headings used in a catalog or repository. This process is called authority control. Example: the Library of Congress Name Authority File


A deprecated proprietary format from Esri that can store multiple spatial geometries, topologies, and attributes.

Data Licenses

Legals statements defining permissions and sharing.

Data Rights

These statements refer to access and usage specifications for datasets

Data vs Metadata

Data is the content you are measuring, collecting, etc. Metadata means data about data and it refers to the information about the content, e.g. who collected it plus where, why, when, and how it was collected. Geospatial metadata describes maps, Geographic Information Systems (GIS) files, imagery, and other location-based data resources.

Dublin Core

A widely used set of key elements designed to be web semantic and interoperable.


A catalog of coordinate system names and parameters originally defined by the European Petroleum Survey Group. Many GIS programs refer to specific coordinate systems by their EPSG number. For example EPSG:32618 refers to WGS 84 / UTM Zone 18N.

Feature extraction

The creation of a GIS feature layer (e.g. shapefile), of features (e.g. points, lines and polygons), from a georeferenced raster file (i.e. scanned map). This process may be manual or automated. Synonyms: vectorization, digitization

Features and Attributes

A feature represents a spatial location (represented, for instance, by a point, polygon, or line) within a GIS dataset; attributes refer to information associated with a given feature. For example, in a point dataset of public schools, school locations (represented by points) are features; information that is associated with these schools (i.e. student population, student:teacher ratio, year founded, school name etc.) are attributes.


Fedora is a digital asset management system. It is only for the underlying architecture (file preservation and storage) and is generally a part of a larger application frameworks that includes discovery and access systems. Note: this is totally separate from the Linux operating system that uses the same name.


FGDC CSDGM (Federal Geographic Data Committee Content Standard for Digital Geospatial Metadata) is a metadata standard for GIS vector and raster data developed in the US in the 1990s. Usually referred to simply as FGDC. The preferable format is XML, but FGDC is also stored as TXT or HTML.


A gazetteer is a geographic index or dictionary to help identify a geographic location associated with a place name. Traditionally, gazetteers were published in conjunction with physical maps and atlases. Digitally, gazetteers function as interoperable data dictionaries for GIS. An example of a gazetteer is GeoNames.


Both an open source software application and the community supporting it. GeoBlacklight is a multi-institutional, open source discovery software application for geospatial content, including GIS data and maps. Based on the open source software project Blacklight, GeoBlacklight began in 2014 as a collaboration by MIT, Princeton, and Stanford. GeoBlacklight has since been adopted by over 25 academic libraries and cultural heritage institutions.

GeoBlacklight Metadata Schema

The GeoBlacklight Schema is a metadata schema for geospatial resource discovery that is closely based upon Dublin Core with the addition of geospatial elements and application-specific fields.


The process of taking text-based location descriptions (such as mailing address) and converting it to geographic information, often coordinates


A set of tools found in the OpenGeoMetadata GitHub repository that can be used for some batch metadata transformations and harvesting. (mainly for GeoBlacklight)


A proprietary ArcGIS file or database format that can hold multiple geometry types, spatial referenece, attributes, and behavior for data OR a generic term for a spatial database.


GeoJSON is a specific type of JSON for encoding spatial data. As an open standard, it is endorsed by preservation organizations, such as the Library of Congress. However, it can be unwieldy for large datasets, as it is a flat file format, not a database. NOTE: a common misconception is that the GeoBlacklight metadata schema uses GeoJSON. This is incorrect - it uses JSON with a few geospatial-related elements. There is also a TopoJSON that extends geoJSON to include topology. However, TopoJSON is not yet an endorsed standard.


GeoNames is a database providing standard vocabulary for geographic place names, given in WGS84 coordinates

Georectification and Georeferencing

(These words were once slightly different but are now used interchangeably.) The process of relating the internal coordinate system of an image to a ground system of geographic coordinates, so that the image can be used for spatial analysis of points on the Earth's surface. Georeferencing can be accomplished in a variety of software applications, including some that are browser-based, and the images are stored in a variety of formats, but GeoTIFFs and GeoPDFs are the most common.

Georeferenced scanned map

A special format where a scanned image has a linked file that stores spatial information. This allows the scanned map to be viewed as a layer in a GIS program or on a digital map.


GeoServer is an open source server written in Java that allows for sharing, processing and editing geospatial data. It is an easy way to connect existing information to platforms that highlight geospatial data such as Leaflet, OpenLayers, virtual globes, and GeoBlacklight. Designed for interoperability, it uses open standards to publish data from spatial data sources.


This term means to add geospatial metadata to media. It is often confused with georeference, but is more specifically considered a metadata attribute. In practice, geotagging typically entails adding one coordinate or point that is used to locate a photo or media object.


a TIFF image file with geospatial information embedded with it.

Groundhog Day references (and why we have them)

Geo4Lib Camp has always been held just before or just after February 2, Groundhog Day. During one conference, a plan for a speaker fell through at the last minute, and the Geo4Lib Camp organizers asked several attendees, including Andrew Battista, to give an impromptu talk. Andrew has a long personal tradition of writing essays that apply some academic discipline or critical method to the film Groundhog Day (1993). Andrew gave a talk on a Spatial Humanities reading of the film, and while strange, the talk was well-received. It has become somewhat of a tradition for Andrew to give a short talk each year about Groundhog Day. See the 2020 talk at


Spoken as "Triple eye eff" or International Image Interoperability Framework. A standardized technique for sharing images on the web. IIIF specifies APIs in the form of JSON files that can be displayed via several different image viewers.

Index map

An index map is a geospatial data discovery tool that allows users to organize, find, and contextualize the individual maps or datasets that constitute a broader collection of geospatial data. It typically delineates the geographic area encompassed by a given collection; individual records that correspond with particular locations are superimposed on this general map, allowing users to effectively browse a collection based on the locations its constituent elements.


Ingest is similar to accessioning, but is more specifically referring to the process of adding data or metadata into a database or application.


Islandora is a community that focuses on digital repository systems using stacks of existing technologies. Basic stack: Fedora (repository) + Solr (search index)+ Drupal (discovery interface)

ISO 19110

This is an additional, optional XML file that can be created that contains the feature catalog, a listing a dataset's attribute types along with information including definitions, descriptions, and frequencies.

ISO 19115

A standard from the International Standards Organization developed in the early 2000s intended for many types of geospatial resources. Can include web services and URIs

ISO 19139

The XML expression of the ISO 19115 standard. It contains identification, constraint, extent, quality, spatial and temporal reference, distribution, lineage, and maintenance of the digital geographic dataset.


The JSON file format is an open standard for data exchange. It consists of objects, key:value pairs, and arrays. GeoBlacklight metadata records are expressed as JSON files. Note: JSON can be thought of as a more lightweight alternative to XML files.


This stands for JSON-Linked Data. This open standard is formatted to include specifications for linked data, such as URIs and relationships. There is also a geoJSON-LD format.


Leaflet is an open-source JavaScript library that helps developers build webmaps on mobile as well as desktop platforms.

Linked Data

Linked Data is the engine of the Semantic Web, a term used by World Wide Web creator Sir Tim Berners-Lee to describe a future Web of Data, wherein the Web will be organized via interlinking, interoperable data instead of collections of pages. Linked data is structured ontologically, with standard vocabularies and unique identifiers, so that it can be queried, added to, and repurposed by any machine or human language. Example: GeoNames has a Linked Data ontology. ;

MARC (MAchine Readable Cataloging)

A general metadata standard developed in the 1960s and universally adopted by libraries. Most libraries have MARC metadata for their map collections.

Metadata Application Profile

A more specific implementation of a schema, designed for a particular use case or software

Metadata Crosswalk

A set of specifications for transforming metadata elements from one schema to another. This allows for metadata harvesting and record exchanges.

Metadata Schema

How metadata is structured: the fields and the types of values

Metadata Standard

To become a metadata standard, a schema needs to be adopted and officially endorsed by a standards-body.


A metadata standard that is a cross between MARC and Dublin Core. Mostly used by the digital repository application Fedora


OpenGeoMetadata is a platform for sharing geospatial metadata files. It is currently structured as a GitHub organization with repositories for each institution. OpenGeoMetadata has been most commonly used for harvesting GeoBlacklight schema metadata files from other institutions


A geospatial platform and community that pre-dates GeoBlacklight.

Open-source software

A software application is considered open source if its source code is freely available to users, who can expand, adapt, modify, and distribute this code as they see fit. Open source software is typically developed collaboratively; as a result, it is important to be able to systematically track changes to the codebase, and to track different versions of a project that result from these changes. Git is a version control system that facilitates collaboration on open-source projects (such as the Geoblacklight project) by allowing participants to essentially track changes and follow each others' work. Github is a web platform that allows users to collaborate on open-source projects using the Git version control system. In the context of Github, a pull request is a procedure wherein someone who wishes to make changes to a project's codebase requests a member of the project team to review these proposed changes; if the reviewer approves these changes, they become incorporated (or merged) into the main codebase.


OpenIndexMaps is a specific index map standard (encoded in GeoJSON format), that is used by the GeoBlacklight community.

PostGIS and PostGres

Postgres, also known as PostgreSQL, is a free and open-source object-relational database management system (RDBMS). Its purpose is to manage data, no matter whether datasets are large or small, in an extensible environment where developers can customize its functionality with data types, functions, etc. PostGIS is an extension of PostgreSQL that adds support for geographic objects. and


In order to make a map, one has to represent the three-dimensional surface of the earth on a two-dimensional plane. There are different ways in which one might flatten the earth to represent it on a two-dimensional map, and these different flattening algorithms (all of which involve distortions of one kind or another) are referred to as map projections. Most maps published on the web are in the Web Mercator projection. Related terms: CRS (coordinate reference system) or the older term SRS (spatial reference system)


A type of spatial data that uses geographically referenced grid cells/pixels, which are associated with data on attributes of interest (i.e. temperature, elevation, population etc.), to represent real-world phenomena.

Raster Dataset

A raster format used in ArcGIS Geodatabases OR a generic term for a raster file.

Research, licensed, and open data

Research data refers to data that has been collected and compiled by researchers affiliated with a given institution (and often released in conjunction with a publication or journal article). Licensed data is data (or a particular interface to data) that an institution (i.e. an academic library) purchases for use by its affiliates. Openly available data (for instance, municipal data) is data that was neither purchased by an institution nor created by its researchers, but which is freely available to the public, and therefore often ingested or indexed by academic libraries to facilitate discovery and preservation.


Samvera is a community that focuses on digital repository systems using stacks of existing technologies. Basic stack: Fedora (repository), Solr (search index), and Blacklight (discovery interface).


An open source geospatial vector data format containing a small bundle of files. Note: the mostly open specification, only covers the .shp, .shx, and .dbf components (notably, .prj is not specified!)


A proprietary hosted platform for distributing many forms of data, including geospatial. Socrata is used by many cities to distribute their tabular data.

On pull requests:;; On Git and Github:


Solr, or Apache Solr, is an open-source enterprise search platform writtin in Java. It runs as a standalone full-text server with faceted search, real-time indexing, dynamic clustering and database integration capabilities. It has a configuration that allows for connection to many applications without Java coding and architecture for further customization. It is the indexing system that sits under Blacklight.

Spatial data infrastructure components

A spatial data infrastructure is a digital apparatus (comprised of interconnected applications and repositories) that facilitates geospatial data storage, discovery, and long-term preservation. Geoblacklight is an application that allows users to discover geospatial data, access relevant metadata, preview layers, and download GIS datasets. Geoserver is an open-source server that allows for GIS data sharing; more specifically, in the context of the Geoblacklight application, it facilitates layer previews and downloads. Institutions that use Geoblacklight as a spatial data discovery platform typically also preserve these underlying datasets in the context of an institutional repository, as well as share relevant metadata through OpenGeoMetadata (a metadata repository that allows institutions to index geospatial data owned by other institutions, and hence data discoverable on their local Geoblacklight instances). There are many moving parts in a spatial data infrastructure; for a more detailed explication of these parts and how they fit together, see the narrative description authored by NYU Data Services.


Sprints refer to an intensive period of time (usually 1-2 weeks) set aside to make significant progress on something. This is a popular concept in many software development practices, such as Scrum. The GeoBlacklight community holds sprints two times per year, and many institutions hold local sprints for their own applications. Although sprints are often thought of as for coding and development, the GeoBlacklight community follows a model in which sprints can address any type of issue, from documentation to metadata to governance and more.

Un-georeferenced scanned map

A scanned map stored as an image file, such as TIFF or JPEG. The presence of coordinates in the record’s metadata does not make the map georeferenced.


Unconferences are intended to be led by participants, with discussion topics developed collaboratively at the start of the event. Unconferences feature minimal formal presentations and emphasize group discussions, knowledge sharing, and impromptu demonstrations. Geo4LibCamp is an unconference.


A type of spatial data that uses geocoded points, lines (connected points), and polygons (an enclosed shape defined by connected lines) to represent real-world phenomena.

Web services

Web services are specific types of APIs used for sharing data. These are especially useful for geospatial data, which cannot be rendered in browsers in their native formats. They are also helpful for users who do not have access to GIS desktop software.


The Web Feature Service (WFS) standard is a Web protocol from the Open Geospatial Consortium (OGC) that serves geographical feature queries over HTTP connections that can be spatially analyzed. It is used by major open-source and proprietary mapping software

WGS 84

WGS 84 is shorthand for World Geodetic System 1984, the common latitude/longitude coordinate system use by GPS devices and many datasets

Who’s on First

A gazetteer for linked data created by Mapzen. (No longer actively developed)


The Web Map Service (WMS) standard is a Web protocol from the Open Geospatial Consortium (OGC) that serves geospatial images over HTTP connections. It is used by major open-source and proprietary mapping software