Worked on improving documentation quality in the taosdata/TDengine repository, focusing on clarifying the behavior of the NVL2 function. Addressed a documentation bug by updating Markdown files to accurately describe the function’s logic, ensuring that if the first expression is not null, the second is returned, otherwise the third. Emphasized documentation QA and alignment to reduce user confusion and support overhead. The work involved careful review and precise editing, with well-annotated commits that enhance traceability and future maintenance. Demonstrated attention to detail and a methodical approach to documentation using Markdown, reinforcing the maintainability of core function documentation.