Can't find docs for some fields in audio analysis response

[loganyang]

I'm using spotipy to hit the API's audio analysis endpoint, the response has

dict_keys(['meta', 'track', 'bars', 'beats', 'sections', 'segments', 'tatums'])

I referred to this page https://developer.spotify.com/documentation/web-api/reference/tracks/get-audio-analysis/

But couldn't find the definition of  a lot of fields in the `track` object, such as codestring, rhythmstring and synchstring, etc. Can someone help me find the definitions?

Also, where can I find some examples how these audio analysis features are used? Any particular use cases? Thanks in advance.