# Biological Expression Language > domain specific language for causal, correlative, and associative biological relations **Wikidata**: [Q61047486](https://www.wikidata.org/wiki/Q61047486) **Source**: https://4ort.xyz/entity/biological-expression-language ## Summary Biological Expression Language (BEL) is a domain-specific language designed to represent causal, correlative, and associative biological relations. Functioning as a formal text-based programming language, it enables the communication of biological instructions to machines for processing and analysis. The language is maintained by a dedicated committee and has evolved through multiple stable versions, distinct from other standards like SBML or BioPAX. ## Key Facts - **Classification:** Instance of a domain-specific language, programming language, and text file. - **File Extension:** Uses the `.bel` extension with a media type of `text/plain`. - **Creator:** Dexter Pratt. - **Current Maintainers:** John Bachman, William Hayes, Charles Tapley Hoyt, Natalie L Catlett, and the Biological Expression Language Committee. - **Version History:** - **Version 1.0:** Released July 2012. - **Version 2.0:** Released June 2014. - **Version 2.1:** Released December 10, 2018. - **Version 2.2:** Released September 24, 2019. - **Web Presence:** Originally hosted at `openbel.org`; migrated to `biological-expression-language.github.io` on May 9, 2020. - **Differentiation:** Distinct from Systems Biology Markup Language (SBML), BioPAX, and Systems Biology Graphical Notation (SBGN). - **Github:** Username `biological-expression-language` with the topic `biological-expression-language`. ## FAQs ### What is the primary function of Biological Expression Language? BEL serves as a domain-specific language used to encode causal, correlative, and associative relationships in biology. It allows researchers to write instructions regarding biological interactions that machines can process. ### Who is responsible for creating and maintaining BEL? The language was created by Dexter Pratt. It is currently maintained by a group of individuals including John Bachman, William Hayes, Charles Tapley Hoyt, and Natalie L Catlett, alongside the Biological Expression Language Committee. ### How does BEL differ from other biological standards like BioPAX or SBML? BEL is explicitly defined as being different from the Systems Biology Markup Language (SBML), BioPAX, and Systems Biology Graphical Notation (SBGN). While these other standards focus on markup or graphical notation, BEL functions as a domain-specific programming language and text file format. ### Where can the official specifications and resources for BEL be found? The language’s resources are currently hosted on GitHub at `biological-expression-language.github.io`. This site succeeded the previous official website, `openbel.org`, which was active until May 9, 2020. ## Why It Matters Biological Expression Language bridges the gap between complex biological knowledge and computational analysis. By providing a structured syntax for biological relationships—causal, correlative, and associative—it allows scientists to represent hypotheses and knowledge in a format that computers can execute, validate, and integrate. Unlike general-purpose programming languages, BEL is tailored specifically for the biological domain, enabling precise modeling of biological mechanisms rather than just software behavior. Its evolution through multiple versions over the last decade demonstrates its ongoing relevance and adaptation to modern biological research needs. ## Notable For - **Specialized Biological Semantics:** Uniquely designed to handle causal, correlative, and associative biological relations, distinguishing it from general programming languages. - **Distinct Standard:** Operates independently of other major biological standards like Systems Biology Markup Language and BioPAX. - **Open Development:** Maintained transparently by a specific committee and named contributors on GitHub. - **Persistent Evolution:** Has maintained a steady release schedule from Version 1.0 in 2012 to Version 2.2 in 2019. ## Body ### Definition and Classification Biological Expression Language (BEL) is a domain-specific language and a subclass of programming language. It functions as a text file format (media type `text/plain`) used to communicate instructions to a machine regarding biological data. Unlike general languages that support various paradigms like object-oriented or functional programming, BEL is optimized for defining biological relationships. ### History and Versioning The development of BEL has been marked by several stable releases, indicating an active and evolving standard: - **Version 1.0:** The initial specification was released in July 2012. - **Version 2.0:** A major update released in June 2014. - **Version 2.1:** Released on December 10, 2018, introducing specific enhancements. - **Version 2.2:** The current noted stable version, released on September 24, 2019. ### Governance and Community The language was created by **Dexter Pratt**. Ongoing maintenance is managed by the **Biological Expression Language Committee** and a team of maintainers including **John Bachman**, **William Hayes**, **Charles Tapley Hoyt**, and **Natalie L Catlett**. The project has a strong presence on GitHub under the username `biological-expression-language`, where the community engages via the topic `biological-expression-language`. ### Web Resources and Archival The official home of BEL has transitioned over time: - **Legacy Site:** `https://openbel.org` (active until May 9, 2020). - **Current Site:** `https://biological-expression-language.github.io` (active from May 9, 2020). ### Relationship to Other Standards BEL is explicitly distinct from other established biological informatics standards. It is listed as "different from" **Systems Biology Markup Language (SBML)**, **BioPAX**, and **Systems Biology Graphical Notation (SBGN)**, positioning it as a unique tool for encoding biological knowledge rather than just markup or graphical display. ## References 1. [Source](https://medium.com/bel-news/bel-2-1-enhancements-ac79b078ad5a) 2. [Source](https://medium.com/bel-news/bel-v2-2-enhancements-cfb4b27b22cb) 3. [Source](https://github.com/OpenBEL/language/raw/master/docs/version_2.0/bel_specification_version_2.0.pdf) 4. [Source](https://github.com/OpenBEL/language/raw/master/docs/version_1.0/bel_specification_version_1.0.pdf)