This NIP is not yet in main. Here is an overview of PRs referencing this NIP. 
Reconcile NIP-96 and NIP-98 and address implementation challenge OPEN @Ademan
Update 98.md CLOSED @viapek
Fix Authorization header string MERGED @dcadenas
Remove all NIP authors MERGED @fiatjaf
Spelling and clarifcations MERGED @gsovereignty
Add Rust implementation of NIP-98 CLOSED @utxo-one
NIP-98 HTTP Auth MERGED @v0l