
Environmental Data Coding Specification
Introduction

Purpose
This International Standard provides mechanisms to unambiguously specify objects used to model environmental
concepts. This is accomplished by specifying a collection of nine EDCS dictionaries of environmental
concepts and a
functional interface.
This International Standard defines EDCS dictionaries for the following categories of information:
- classifications: specify the type of environmental objects,
- attributes: specify the state of environmental objects,
- attribute value characteristics: specify information concerning the
values of attributes,
- attribute enumerants: specify the
allowable values for the state of
an enumerated attribute,
- units: specify quantitative measures of the state of some environmental objects,
- unit scales: allow a wide range of numerical values to be stated,
- unit equivalence classes: specify sets of units that are mutually comparable,
- organizational schemas: useful for locating classifications and attributes sharing a common
context, and
- groups: into which concepts sharing a common context are collected.
Design criteria
This International Standard was developed to fulfil the following requirements:
- flexibility and extensibility: accommodating growth by registration.
- information: define what objects are (classifications), what the states of objects are (attributes), and how
values of state are characterized (data types, units of measure, and
unit scales).
- use international standard units: adopt the International System
of Units.
- interoperate with existing domain-specific approaches: build on the experience gained by other
organizations, including IHO, WMO, and
DGIWG, in developing information coding systems.
- organization: structure for efficient access.
- orthogonality: separate the concepts of type and state of environmental objects.
- rigor: provide unambiguous and clearly defined concepts.
- separate units of measure from attributes:
relate units of measure to attributes through unit equivalence
classes.
- unification: define a comprehensive set of general principles and specific concepts that allows
environmental information to be shared among different communities.

http://www.iso.ch/iso/en/ittf/PubliclyAvailableStandards/ISO_IEC_18025_Ed1.html