This chapter presents some of the concepts, vocabulary, and standards underlying the &geot; application. Geotools uses certain terms in very specific ways. The terms used to refer to geospatial information come from a set of standards developed by the International Organization for Standardization (ISO) and the Open Geospatial Consortium (OGC). These standards, for example, use the term 'Feature' to describe the fundamental unit of geospatial information: both real physical entities such as rivers and abstract ideas such as property boundaries. The best introduction to this terminology is the general introduction written by the OGC, the OGC Reference Model, specification number 03-040. Term Definition Feature The fundamental unit of geospatial information which may be a real physical entity, such as a river, or an abstract conceptual notion, such as the geoid. Coordinate Referencing System The metadata required to link a coordinate to an actual spatial location defined relative to the physical globe. The term is commonly shortened to CRS. Datum Refers to several concepts all related to anchoring a system of coordinate reference to known or defined points in the real world. Datums may be spatial or temporal. Spatial datums refer to known points on the globe whereas temporal datums refer to defined instants in time used to define the endpoints of an epoch. Spatial datums may refer only to the actual locations used to anchor a coordinate system or may refer to a unit of metadata including the locations plus a definition of a coordinate system and a prime meridian. Geoid Geoids are conceptual surfaces of equipotential gravitational attraction which are modern equivalents to the idea of a globally equal "Mean Sea Level" from which geodedic altitudes could be derived. Global geoids are commonly defined using a spherical harmonic model. Local geoids may be defined using a grid of points and a triangular irregular network function to calculate the values between the points. &geot; is explicitly designed to implement the fundamental international standards for geospatial application. This included, first of all, the standards promulgated by the Open Geospatial Consortium (OGC). Those standards have been partially superceeded by newer standards proposed by the International Organization for Standardization (ISO). &geot; also uses common standards provided by other ogranizations, notably the database of coordinate reference systems and transformations provided by the Surveying and Positioning Committee of the International Petroleum Organization still called, for historical reasons, the European Petroleum Survey Group (EPSG). The GeoAPI file org.opengis.annotation.Enum has a partial list of these standards. The Technical Committee 211 has an overview of their work avaialable here>. Spec # Title GeoAPI package Geotools package OGC Equivalent 19101 Reference Model 19101 Reference Model Part2: Imagery 19103 Conceptual Schema Language org.opengis.util org.geotools.util 19104 Terminology 19105 Conformance and Testing 19106 Profiles 19107 Spatial Schemal for Feature Geometry org.opengis.spatialschema.geometry JTS (org.geotools.geometry) Abstract Topic 1 19108 Temporal Schema 19109 Rules for Application Schema 19110 Methodology for Feature Cataloging 19111 Spatial Referencing by Coordinates org.opengis.referencing org.geotools.referencing Abstract Topic 2 19112 Spatial Referencing by Geographical Identifier 19113 Quality Principles 19114 Quality Evaluation Procedures 19115 Metadata org.opengis.metadata org.geotools.metadata Abstract Topic 11 19115-2 Metadata Part2: Extensions for imagery and gridded data 19116 Positioning Services 19117 Portrayal 19118 Encoding 19119 Services 19120 Functional standards 19121 Imagery and gridded data 19122 Qualifications and Certification of personnel 19123 Schema for Coverage Geometry and Functions 19124 Imagery and Gridded Data Components 19125-1 Simple Feature Access Part1: Common architecture 19125-2 Simple Feature Access Part2: SQL option 19125-3 Simple Feature Access Part3: COM/OLE option 19126 Profile - FACC Data Dictionary 19127 Geodetic Codes and Paramters 19128 Web Map Server Interface (SLD?) org.opengis.layer org.geotools.layer 19129 Imagery, Gridded and Coverage Data Framework 19130 Sensor and Data Models for Imagery and Gridded Data 19131 Data Product Specification 19132 Location Based Services Possible Standards 19133 Location Based Services Tracking and Navigation 19134 Multimodal Location Based Services for Routing and Navigation 19135 Procedures for registration of Geographic Information Items 19136 Geography Markup Language 19137 Generally Used Profiles of the Spatial Schema and of Similar Important other Schemas 19138 Data Quality Measures 19139 Metadata - Implementation Spec # Topic Title GeoAPI package Geotools package ISO Equivalent 03-040 OGC Reference Model none none 99-101r1 Abstract 0 Abstract Specification Overview 01-101 Abstract 1 Feature Geometry ISO 19107 04-046r3 Abstract 2 Spatial Referencing by Coordinates ISO 19111 99-103 Abstract 3 Locational Geometry Structures ISO 19111 99-104 Abstract 4 Stored Functions and Interpolation 99-104 Abstract 5 Features 99-106 Abstract 6 Coverage 99-107 Abstract 7 Earth Imagery 99-108r2 Abstract 8 Relationships between Features 99-109r1 Abstract 9 Quality 99-110 Abstract 10 Feature Collections 99-111r1 Abstract 11 Metadata 99-112 Abstract 12 Service Architecture 99-113 Abstract 13 Catalog Services 99-114 Abstract 14 Semantics and Information Communities 99-115r2 Abstract 15 Image Exploration Services 99-116r2 Abstract 16 Image Coordinate Transformation Services 01-104 Implementation Grid Coverage ISO 19123 01-009 Implementation Coordinate Transformation Services extends ISO 19111 01-029 Implementation Geographic Markup Language 2.0 99-049 Implementation Simple Features for SQL 02-059 Filter Encoding Specification org.opengis.filter 02-070 Styled Layer Descriptor org.opengis.sld 03-064 GO-1 Application Objects org.opengis.go ext/go org.geotools.display 04-024 Web Mapping Service ?org.opengis.layer 04-094 Web Feature Service ?org.opengis.feature Specification Title Base package EPSG Tech. Note 7 Part I EPSG Tech. Note 7 Part II