Understanding the codes
A letter coding system has been adopted in preference to a
fully numerical coding system or an alpha-numeric system (as used
in the NVC and EUNIS systems). This has a number of advantages. It
enables the construction of intuitive codes which can readily be
related to their respective types without recourse to the full type
title. Furthermore, it enables changes to the order in which the
types are presented without the need to change a numerically
sequenced code. This was particularly useful in the early
development phase of the classification, but has continued to be of
use during subsequent revisions of the classification.
Construction of codes follows a few simple rules, which
achieve consistency throughout the classification whilst aiming to
keep the resultant codes relatively short and intuitive.
Familiarity with the rules for code construction and with the types
themselves, by those working regularly with the classification,
results in rapid use of codes as a short-hand means of referring to
the types defined.
Codes are defined for each level in the classification. Within
a level, they comprise one or several elements. They are based on
the following rules:
Broad habitat and main habitat codes are based on habitat factors
or gross biological features (e.g. macrophytes and biogenic
Biotope complex, biotope and sub-biotope codes are based wherever
possible upon the most characteristic taxa (which preferably also
dominate spatially/numerically) (preferably no more than two per
biotope complex, biotope or sub-biotope).
Where the biological composition is too complex to derive a simple
code, features of the habitat are used (e.g. VS for variable
Codes for habitat factors, higher taxa and descriptive community
features (e.g. park, crustose) are derived from a standard lexicon
. A full list of
codes used is contained in the hierarchical list which can be
downloaded from the classification website.
Codes for names of genera are derived using the first three letters
of a genus or higher taxon name (e.g. Ala for
Alaria, Chr for
Chrysophyceae). Codes for species names are
derived using the first letter of the genus and the first three
letters of the specific name (e.g. Ldig for
Within the code each new element of the code starts with a capital
As far as practical the code elements are unique, but some
duplication is adopted in the interests of keeping codes short. The
code for any given type (i.e. for the level defined, regardless of
whether it is stringed with higher codes – see below) is always
All the biotope/sub-biotope codes are unique, so users familiar
with the classification can refer to individual biotopes using only
the codes for these levels in the hierarchy.
The full codes are compiled using the code for each level in the
hierarchy, separated from the next level by a full stop, starting
with the broad habitat (level 2), followed by the main habitat,
biotope complex and so on. For example LS.LSA.MoSa.AmSco.Eur:
Amphipods and Scolelepis spp.
NOTE: to avoid confusion, others using the
classification should not erect similar codes for types not
currently described in the national classification.