Agrovoc (Thesaurus) Model
The agrovoc database is a specialized model designed for managing Multilingual Thesauri. It adheres to standards for controlled vocabularies (like ISO 25964), allowing for the management of hierarchical (BT/NT), associative (RT), and equivalence (USE/UF) relationships.
While named "Agrovoc" (based on the FAO agricultural thesaurus), this structure can be used for any controlled vocabulary.
Database Definition
- Internal Name:
agrovoc - Type: Authority / Thesaurus
- Languages: Configured for English, French, and Spanish (expandable).
1. Field Structure (FDT)
The Field Definition Table uses a Language Block logic. Each language has a dedicated range of tags (Hundreds), but the last two digits represent the same semantic relationship across all languages.
Tag Logic
- 0xx: English (Main language in this config)
- 1xx: French
- 2xx: Spanish
Semantic Fields
These relationships are standard for Thesaurus construction.
| Suffix | Relationship | Name | Definition |
|---|---|---|---|
| 01 | Descriptor | DE | The preferred term used for indexing. (e.g., Tag 1, 101, 201) |
| 02 | Scope Note | SN | Definition or usage note for the term. |
| 03 | Equivalence | USE | Points to the preferred term (e.g., "Farming USE Agriculture"). |
| 04 | Equivalence | UF | Used For. The non-preferred synonyms (e.g., "Farming"). |
| 05 | Hierarchy | BT | Broader Term. The parent concept (e.g., "Fruit" is BT of "Apple"). |
| 06 | Hierarchy | NT | Narrower Term. The child concept. |
| 07 | Associative | RT | Related Term. Concepts associated but not hierarchical (e.g., "Cow" RT "Milk"). |
| 08 | Note | ND | Administrative or history note. |
| 94 | ID | ID | Unique numeric identifier for the concept (language independent). |
2. Indexing Strategy (FST)
The Field Selection Table (agrovoc.fst) creates access points mainly for the primary language (English in the default file), allowing users to search by any type of relationship.
| Prefix | Relationship | Technique | Usage |
|---|---|---|---|
| DE_ | Descriptor | Phrase (0) | Searching exact authorized terms. |
| PER_ | Permuted | Word (8) | Searching individual words within terms. |
| USE_ | Use | Prefix (5) | redirecting from non-preferred terms. |
| UF_ | Used For | Prefix (5) | Finding which term replaces a synonym. |
| BT_ / NT_ | Hierarchy | Prefix (5) | Navigating up and down the tree. |
| RT_ | Related | Prefix (5) | Finding associated concepts. |
| TT_ | Global | Word (8) | General keyword search across all fields. |
To enable full searching in French and Spanish, the administrator must add lines to the .fst replicating these rules for tags 101-108 and 201-208.
3. Visualizing Data (PFT)
The display format (agrovoc.pft) presents the term and its relationships in a clean table.
- Format: HTML Table.
- Logic: It iterates through all language blocks. If a French term exists (e.g., Tag 101), it displays it under the label "DE (FR)".
- Usage: This allows catalogers to see the translation of a term immediately alongside its hierarchical relations.
4. Usage in ABCD
This database is rarely used "stand-alone". It is designed to be linked to bibliographic databases (like books or marc) via Authority Control.
- In the Bibliographic FDT: You configure a field (e.g., Subject - Tag 650) to "Pick" values from
agrovoc. - The Lookup: When a librarian types "Agri...", the system searches
agrovoc, retrieves the authorized descriptor "Agriculture", and pastes it into the book record.