Implementing the ILAE 2025 seizure taxonomy in medical software

The International League Against Epilepsy (ILAE), working via a multidisciplinary task force, has issued a position paper with updated seizure classification guidelines (2025) replacing its previous guidance (2017), establishing a revised de-facto standard for clinical assessment and classification of epileptic seizures. The 2025 model simplifies the system, making it easier to adopt in different clinical settings while also clarifying the taxonomic rules, the definition of consciousness, and the application of phenomena-based descriptors. As a result, clinical practitioners, technologists, and medical software developers also face the challenge of adopting the new standard in their applications and workflows. To aid in the realization of this update in medical device software, this article presents a proposed numerical structure for ILAE 2025 edition of the seizure classification system as a definition of interacting bitfields, establishing an open reference implementation to support common storage and interoperability between software environments. Assigning each orthogonal concept to a single bit, we encode the core ontology and expanded descriptor set so that they fit into 32-bit and 128-bit unsigned integers, respectively. TypeScript, known for its expressiveness and practical applicability, is used as the implementation language for these definitions. Examples are provided to help implementers incorporate the proposed specification into their software, as well guidance for mapping from the ILAE 2017 type system to the updated ILAE 2025 type system. The reference specification, with test cases and examples, is maintained in a public code repository and available under a permissive license.