New mandoc feature: -T html -O toc (Table of contents)

It's really cool how they solved it without breaking backward compatibility or the interface: unless specifically requested, mandoc(1) will work as before, but the overall capability of the software has been enhanced. That's what I call system engineering.

Neovim's ":Man" command also shows a ToC when you type "gO" (mnemonic: "outline").

See also:

    :help gO

Currently Nvim builds this ToC with its own hacks, so it would be nice to get that info from mandoc instead. But IIUC, "-O toc" only works with HTML output of mandoc? How can non-HTML tools get the ToC from mandoc?

mandoc is great! It could replace legacy man almost everywhere