Transcode variable bit rate audio

[NOYB]

Is there support for sout transcode variable bit rate audio?

The command-line help wiki tells us the following. But is there a special meaning for say 0 (zero)? Such as variable bit rate.
Setting ab=0 transcodes. But don't know what it's doing? Is it vbr or something else such as a default?

https://wiki.videolan.org/VLC_command-line_help/

--sout-transcode-ab=<integer>
Audio bitrate
Target bitrate of the transcoded audio stream.