What does `-map data-re` option in FFMPEG do?

Question

I am trying to extract and parse KLV data from a video stream. I found the following example in a Github repository. I am wondering what does the mapping option data-re do?

$ ffmpeg -i Day\ Flight.mpg -map data-re -codec copy -f data - 

I understand the rest of the command, and know that -map is used to choose streams from inputs. But what does data-re mean. I couldn't find any explanation for it (or similar mapping option or stream identifier) in the documentation, e.g. here and here.

Answer 1

It's a typo and incorrect. The only time you use arbitrary label names is when using -filter_complex.

Use:

$ ffmpeg -i Day\ Flight.mpg -map 0:d -c copy -f data -

I could understand a user trying data, but data-re? Might be a double typo for -map data -re, where -re is intended to be the "Read input at native frame rate" input option (-map data is still invalid in this case).