In my real problem, the presence of this "fig:" makes image links vulnerable to breakage via the insertion of a hard line break at the space before "fig:". Therefore I have to also manipulate text wrapping, i.e. set --wrap=none or --wrap=preserve to protect the links.

On Friday, October 13, 2017 at 10:31:12 AM UTC-7, John MacFarlane wrote:

It's a kludge we use to distinguish images that should be
treated as figures.  You can turn off the extension
entirely using

    -f markdown-implicit_figures

I can also change the CommonMark writer so that the "fig:"
prefix is removed, as it is in the other Markdown writers.

+++ Jennifer Bryan [Oct 13 17 09:44 ]:
>   Why does the title "fig:" get inserted into this image link and, more
>   importantly, how can I prevent that?
>   $ echo '' | pandoc -f markdown -t commonmark
>   
>   It appears to be fairly specific to CommonMark, i.e. it's not there for
>   other flavours of markdown.
>   $ echo '' | pandoc -f markdown -t markdown_github
>   
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