Worked on the lichess-org/api repository to clarify API documentation for custom initial chess positions, addressing a terminology inconsistency by replacing FEN references with X-FEN. This update improved the accuracy and clarity of the API specifications, reducing the risk of integration errors for developers using the documentation. The work involved precise edits in YAML files and careful formatting to maintain documentation consistency, utilizing pnpm for automated formatting tasks. All changes were made traceable through a specific commit, supporting reproducibility and peer review. The contribution focused on documentation quality, demonstrating attention to detail and collaborative practices in software development and API documentation.