We use the term "domain collections" to refer to a continuum of knowledge representation where words are used to organize or categorize information. Some example formats are described below:
- Vocabularies - Vocabularies can be merely word lists such as "the colors of the rainbow". They may be used to prescribe an acceptable set of word choices such as authority files, or controlled vocabularies
- Thesauri - Thesauri are words organized according to their meaning, which contrasts words organized alphabetically (a dictionary). Relationships that might be represented include synonyms, hypernyms, hyponyms or even holonyms.
- Taxonomies - Taxonomies are terms organized in a hierarchy.
- Ontologies - Ontologies are knowledge representation models that are often asked for, but seldom, if ever, used to their fullest potential.
An important challenge of using hierarchically arranged terms is that when power is gained through categorization it can often or even necessarily reduce precision. Therefore, determining the right level of categorization appropriate for a task, depends on the task itself, and the community being served.
In our experience there is not a correct representation for a system of belief outside of a context, unless, of course, the categorization is based on a Linnaean definition of what constitutes membership.