The concept of "best" subtitle format is not described in the docs

[lkintact]

• I'm asking a question
• I've looked through the README and FAQ for similar questions
• I've searched the bugtracker for similar questions including closed ones

On the readme page for youtube-dl (https://github.com/ytdl-org/youtube-dl/blob/master/README.md) a --sub-format option is described:

--sub-format FORMAT              Subtitle format, accepts formats
                                 preference, for example: "srt" or
                                 "ass/srt/best"

It's not quite clear however what exactly the "best" subtitle format is or how what's "best" is determined. Running youtube-dl with --list-subs gives a list of subtitles, but none of them has a (best) mark like the items of video/audio formats in the lists produced with --list-formats.

[dstftw]

This is an implementation detail depending on a particular extractor.

[lkintact]

@dstftw Thank you, Sergey M. Maybe your answer should be reflected in the FORMAT SELECTION of the readme page to prevent future questions similar to mine?