ELSST follows the recommendations of International Standards Organization’s Guidelines ISO 25964-1 (2011): Information and documentation - Thesauri and interoperability with other vocabularies, Part 1.
ELSST is symmetrical, which means that every concept has a Preferred Term in each language, and all language versions share the same structure of hierarchical and associative relationships.
The hierarchical relationship is designated through the Broader Term (BT) and Narrower Term (NT) notation. A BT is broader in scope than its NT.
ELSST supports polyhierarchies (i.e. where a term has more than one BT) only where absolutely necessary.
There are two types of equivalence relationships in ELSST: monolingual equivalence and multilingual equivalence.
The monolingual equivalence relationship holds between a Preferred Term (i.e. the descriptor term that is used for indexing) and its corresponding Use For (UF) term.
UFs are often called 'non-preferred terms', 'entry points' or 'access terms' because they provide users with an 'entrance' or 'beginning' point for their search which will direct them to the appropriate Preferred Term. The user is provided with as many access points to the vocabulary as possible.
UFs may include synonyms, quasi-synonyms, spelling variants, acronyms and antonyms. They may also be used for terms that are narrower in meaning than the Preferred Term with which they have been associated, but which are too specific for the purposes of the thesaurus.
|SINGLE-SEX SCHOOLS||BOYS' SCHOOLS|
Multilingual equivalence holds between Preferred Terms that represent the same concept in each language. English is used as the source language for all target language equivalents.
|Preferred Term (English)||Preferred Term (French)|
|SOCIAL ATTITUDES||ATTITUDES SOCIALES|
Multilingual equivalence is not established between UFs in different languages, since UFs in ELSST may be language-specific.
The associative relationship indicates a close conceptual relationship between terms that is neither hierarchical nor equivalent. It is indicated by the Related Term (RT) notation. The associative relationship is a symmetrical, reciprocal relationship.
|SOCIAL SECURITY||WELFARE POLICY|
|WELFARE POLICY||SOCIAL SECURITY|