This NIP is not yet in main. Here is an overview of PRs referencing this NIP. 
Implement Markdownlint GitHub action OPEN @mariano-perez-rodriguez
Markdown improvements, embelishments, and standardizations CLOSED @mariano-perez-rodriguez
fix grammar and typos MERGED @vivganes
Update all NIPs to include 'depends' and 'mentions' tags OPEN @blakejakopovic
NIP-78: app-specific data MERGED @fiatjaf