Specifications are further tested in other Interoperability Program activities that include:

• Pilot Projects where collaborating user communities apply and test OGC member-developed OpenGIS Implementation Specifications in real world settings using commercial products that implement OpenGIS Specifications for interfaces and encodings. These test environments produce useful feedback for revising existing OpenGIS Specifications and guiding the development of new ones.
• Planning Studies, Insertion Projects, and Feasibility Studies focus on shaping enterprise and domain architectures to support interoperable solutions and integrated solutions that involve geoprocessing. Like Pilots, these initiatives also produce useful feedback into the OGC specification process.
• Outreach and Education: Technical documents, training materials, test suites, reference implementations and other interoperability resources are made available for use by members and/or the public on the OGCNetwork.

OGC Implementation Specifications Overview
There are three levels of Implementation Specifications:

• Approved: These are completed specifications published on the OGC public web site. They have received consensus approval by the Technical Committee and have been approved by the OGC Planning Committee.
• Candidate: A Candidate Implementation Specification is a Discussion Paper for public review, a Request for Comment (RFC), a Recommendation Paper, or a Draft Specification that an OGC Technical Committee Special Interest Group (SIG) has begun to review. Candidate Specifications are typically defined, developed, and tested in the OGC Interoperability Program. The results of this work are published as Draft IP Report or IP Reports.
• Planned: These are specifications are under discussion but not yet part of the formal specification development process. These are not described in this paper. Typically, planned specifications arise from sponsor requests or are unexplored ideas generated during a test bed.

The Interoperability Program has developed specifications for Web Mapping Services, Open Location Services (OpenLS), and Geospatial Fusion Services. Web mapping services are a family of specifications for delivering geospatial data and performing interoperable geoprocessing over the web. Open Location Services are specifications to support mobile geoprocessing across multiple technology platforms.

Geospatial Fusion Services are specifications that facilitate the integration of non-spatial data such as documents, pictures, and audio with spatial data in order to present a complete geographic perspective. This paper will focus on approved specifications for Web Mapping Services because, in general, they are the most mature and applicable to the oil and gas industry.

Approved Spcifications

OpenGIS Simple Features Specification
A Simple Feature is defined by the OpenGIS Abstract specification to have both spatial and non-spatial attributes. Spatial attributes are geometry valued, and simple features are based on 2D geometry with linear interpolation between vertices. The base Geometry class has subclasses for Point, Curve, Surface and Geometry Collection. Each geometric object is associated with a Spatial Reference System, which describes the coordinate space in which the geometric object is defined. The supported geometry types include points, lines, linestrings, curves, and polygons. Feature-to-feature relations are not supported.

The Simple Feature Specification application programming interfaces (APIs) provide for publishing, storage, access, and simple operations on Simple Features. The APIs enable tasks such as the establishment of linear and angular units, spheroids, datums, prime meridians, and map projections. Included are interfaces for common geometric and topological constructs such as convex hull, symmetric difference, closure, intersection, buffer, length, distance, and dozens of others. At the GIS feature level, the API's provide for the creation and management of feature collections and the ability to access features from such collections using geometric, topological, or attribute modifiers.

The Simple Feature Specification is a primary building block for interoperability because it describes a minimum set of geometries for geospatial processing. Many GI software vendors such as ESRI, Intergraph, and Oracle support the Simple Feature Specification.