ISO/IEC 18025:2014 provides mechanisms to specify unambiguously objects used to model environmental concepts. To accomplish this, a collection of nine EDCS dictionaries of environmental concepts are specified:
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.
A functional interface is also specified.
As denoting and encoding a concept requires a standard way of identifying the concept, ISO/IEC 18025:2014 specifies labels and codes in the dictionaries.
ISO/IEC 18025:2014 specifies environmental phenomena in categories that include, but are not limited to, the following:
abstract concepts (e.g., absolute latitude accuracy, geodetic azimuth);
airborne particulates and aerosols (e.g., cloud, dust, fog, snow);
animals (e.g., civilian, fish, human, whale pod);
atmosphere and atmospheric conditions (e.g., air temperature, humidity, rain rate, sensible and latent heat, wind speed and direction);