Standards

This wiki is based on Part C: Standards for fundamental geo-spatial datasets of the Guidelines of Best Practice for the Acquisition, Storage, Maintenance and Dissemination of Fundamental Geo‐Spatial Datasets.

The first part of the wiki provides background information on geo-spatial standardization. A standard and different types of standards are defined; the development and implementation of standards are described; and key standards bodies for fundamental geo-spatial datasets are introduced. Standards relevant for acquiring and maintaining fundamental geo-spatial datasets are introduced, an overview of a number of standards for geo-spatial data formats is provided; standards for data product specifications, data quality, quality assurance, hydrographical surveys and data models for fundamental geo-spatial datasets are described; and finally, a brief overview is provided of standards that one should be aware of when procuring or using products and tools for the acquisition and maintenance of geo-spatial datasets.

The second part of the wiki provides implementation guidelines for metadata and feature catalogue standards used in the dissemination of geo-spatial data, describes map standards and provides a tabular overview of standards used in the dissemination of geo-spatial data over the Web.

The wiki was created and is maintained by the ICA Commission on SDI and Standards (http://sdistandards.icaci.org/).

Types of standards

A standard is a document (or collection of documents), usually but not always published, that specifies requirements, recommendations, conventions and/or guidelines used consistently to ensure that a product, service, system or any other standardization target is fit for its purpose. Standards can be developed and implemented in different ways, and describe different things at different levels of abstraction and/or detail. Table 1 provides an overview of standard deliverables for different purposes. A profile is a set of one or more base standards or subsets of base standards, and, where applicable, the identification of chosen clauses, classes, options and parameters of those base standards, that are necessary for accomplishing a particular function [ISO 19106:2004]. In the geospatial community, profiles for international standards are sometimes developed for national and regional application. For example, SANS 1878-1: 2005, South African spatial metadata standard, Part 1: Core metadata profile, is a profile of ISO 19115:2003, Geographic information – Metadata, developed by the SABS for use in South Africa.

1. ISO/IEC deliverables (Source: ISO/IEC Directives, Part 1 Consolidated ISO Supplement, 2014)

Deliverable	Description
Industry Technical Agreement (ITA)	An ITA aims to bridge the gap between the activities of consortia and the formal process of standardization represented by ISO and its national members. An important distinction is that the ITA is developed by ISO workshops and fora, comprising only participants with direct interest, and is therefore not accorded the status of an International Standard.
International Standard (IS)	An International Standard is a standard that is adopted by an ISO or IEC and made available to the public.
Publicly Available Specification (PAS)	A Publicly Available Specification is developed to respond to an urgent market need,representing either a consensus in an organisation external to ISO or IEC; or a consensus of the experts within a working group. A PAS is not allowed to conflict with an existing International Standard, but competing Publicly Available Specifications on the same subject are permitted.
Technical Report (TR)	A Technical Report contains collected data of a different kind from that normally published as an International Standard or Technical Specification. This may include, for example, data obtained from a survey carried out among the national bodies, data for example, data obtained from a survey carried out among the national bodies, data on work in other international organisations or data on the “state of the art” in relation to standards of national bodies on a particular subject.
Technical Specification (TS)	A Technical Specification is developed when there is the future possibility of agreement on an International Standard, but for which at present the required support for approval as an International Standard cannot be obtained; there is doubt on whether consensus has been achieved; the subject matter is still under technical development; or there is another reason precluding immediate publication as an International Standard.

A standard is concerned with one or more standardization targets (i.e. the object of standardization), for example, a data model, a web service, a system or a process. Table 10.2 lists different levels of abstraction at which standardization targets are described. Table 10.3 describes different types of heterogeneity, which geo-spatial standards aim to overcome. A geo-spatial standard may standardize geographic data, services or procedures at more than one level of abstraction and address more than one type of heterogeneity. However, often a single level and a single type of heterogeneity are prominent in the standard.

2. Different levels of abstraction and detail in standards (Source: ISO 19101-1:2014)

Deliverable	Description
Meta-meta	Meta-meta standards cover the more general aspects of geo-spatial information and serve as foundations for other standards. Examples are ISO 19101:2002, Geographic information – Reference model, and ISO/TS 19103:2005, Geographic information – Conceptual schema language.
Meta	Meta standards standardize aspects of geo-spatial information that are used in other standards and applications. Examples are ISO 19107:2003, Geographic information – Spatial schema, and ISO 19110:2005, Geographic information -- Methodology for feature cataloguing.
Application	Application standards are directly implementable. Examples are ISO 19136:2007, Geographic information – Geography markup language (GML), and OGC KML Version 2.2.0.
Instance	Instance standards are concerned with the standardization of data and services or applications processing data. Examples are the different geo-spatial data formats described in 10.7.1.

3. Four types of heterogeneity (Source: ISO 19101-1:2014)

Type of heterogeneity	Description
System	System heterogeneity exists at the ‘lowest’ level between hardware, operating systems and communication systems. Standards to overcome this type of heterogeneity are typically developed by organisations focusing on general-purpose information and communication technology, such as the ISO/IEC JTC 1, IETF and W3C.
Syntactic	Syntactic heterogeneity concerns the physical representation of data, i.e. the symbols and the grammar used to convey data within a message from a sender to a receiver. Syntactic heterogeneity is concerned with the appearance of the message but not in its content.Examples are different geo-spatial data formats, such as DXF and SHP.
Structural	Structural heterogeneity (also called schematic heterogeneity) is concerned with the differences related to conceptual modelling of geographic features. For example, a street name can be represented either by a single attribute (e.g. ‘Church Street’) or by two attributes, one for the name (e.g. ‘Church’) and the other for the type (e.g. ‘Street’).
Semantic	Semantic heterogeneity refers to the differences in meaning between concepts and data used to represent geographic features. For example, two individuals may perceive a bridge in different ways leading to different concepts: a road infrastructure, an obstacle for marine navigation, a point of interest, etc.

Development of standards

Conventionally, standards are developed by international or national standards organisations, such as the International Organization for Standardization (ISO), and the South African Bureau of Standards (SABS). However, industry consortia are playing an increasingly important role in standards development, both nationally and internationally. Typically, an industry consortium in standards development is a membership organisation formed to ensure performance and quality in a particular industry or economic sector. Examples in the IT industry are the Internet Engineering Task Force (IETF) and World Wide Web Consortium (W3C) and the Open Geospatial Consortium (OGC) in the geo-spatial industry. Industry consortia are seldom accredited by national or international standards organisations, but their standards usually have strong support within a relatively short span of time because they are developed by members of the industries concerned, by consensus of stakeholders and by using an open review and approval process.

A variety of definitions for open standards exist, emphasizing different aspects of openness.

Generally, in the geospatial community open standards refer to standards developed according to the principles of open standards formulated by Bruce Perens (https://en.wikipedia.org/wiki/Open_standard#Bruce_Perens.27_definition). These include the ability of stakeholders to participate voluntarily in standards development, the use of consensus in the review and standards approval process, providing public access to all development documents, maximizing end-user choice by prohibiting vendor lock-in and ultimately providing access to the completed standards to allow royalty-free implementations and extensions. Legally, the developer of an open standard retains all related patents and intellectual property rights but third party users are free to support and create products that conform to it. Geo-spatial standards developed by the ISO, OGC and the International Hydrographic Organization (IHO), as well as IETF and W3C, are generally considered to be open.

Proprietary standards are developed by organisations for their products or services. Developers of proprietary standards have sole ownership and retain all patents associated with the standards, even though they might publish them. Third party users are sometimes allowed to use a proprietary standard, either by paying a prescribed licence fee or free of charge, but they do not play any part in its development and maintenance. In the geo-spatial domain, the Autodesk DXF (Drawing Exchange Format) and Esri shape (SHP) files are examples of proprietary data format standards that have been published.

Public domain standards are not owned or developed and maintained by a particular organisation, but developed collectively by a user community. GeoTIFF is an example of a public domain standard.

Implementation of standards

Standard implementation is either mandatory (de jure) through government legislation andregulations, or voluntary (de facto) through consensus and popular acceptance by the community.Sometimes standards developed by official standards bodies are also referred to as being de jure.

The scope usually appears at the beginning of a standard and defines without ambiguity the subject of the document and the aspects covered, thereby indicating the limits of applicability of the document or particular parts of it.

A standard contains informative and normative elements. Informative elements identify the document, introduce its content and explain its background, development and relationship with other documents; or provide additional information intended to assist the understanding or use of the document. Normative elements describe the scope of the document or set out provisions. Provisions are expressed as

• requirements, i.e. expressions conveying criteria to be fulfilled if compliance with the document is to be claimed and from which no deviation is permitted);
• recommendations, i.e. expressions conveying that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required, or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited;
• permission, i.e. a course of action permissible within the limits of the document; or
• statements of possibility or capability.

Typical verbal forms for requirements are ‘shall’ and ‘shall not’, while ‘should’ and ‘should not’ are used for recommendations. For example, ‘data quality shall be described using the [specified] data quality elements’ (ISO 19157:2013) and ‘a data quality evaluation method should be included for each applied data quality measure’ (ISO 19157:2013). Verbal forms for the expression of provisions are described in Annex H of ISO/IEC Directives Part 2 (2011).

Standards for the acquisition and maintenance of fundamental geo-spatialdatasets

• Implementation of standards
• Key standards bodies for fundamental geo-spatial datasets
• Standards on which other standards are based
• Standards for acquiring and maintaining fundamental geo-spatial datasets
• Data models for fundamental geo-spatial datasets
• Standards for products used in the acquisition and maintenance of fundamental geo-spatial datasets

Standards for dissemination of fundamental geo-spatial datasets

• Introduction
• Metadata standards for disseminating fundamental geo-spatial datasets
• Feature catalogue standards for disseminating fundamental geo-spatial datasets
• Map standards
• Standards for products used in Web dissemination

Acknowledgments

The original document was edited by Derek Clarke with contributions of Serena Coetzee, Antony Cooper and Victoria Rautenbach.

The contribution of Sajani Joshi MSc and Tanzeel Ur Rehman Khan for the creation of the wiki are gratefully acknowledged.

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