Metadata for Markdown YAML

There may not be a write-up yet, or at least one that is modern. I know I’ve shared similar tips long ago, but aimed at the v2 compile engine, where this kind of thing could be done, but only by kludging data into the Title Suffix field.

The Metadata checkbox in the Section Layout pane that you are referring to is not specifically a reference to Markdown metadata—it’s a feature that is available to everything from ePub to PDF to HTML, and simply a basic and one-step way to export internal information about each section of the binder. For Markdown, uses a “code block” to preserve the formatting of the metadata.

Every single thing that this checkbox does can be replicated using the placeholders found in the Help ▸ List of All Placeholders… command. In combination with a Layout tool such as the section Prefix tab, one could easily design their own metadata template, to whatever specification they desired (YAML, XML, HTML meta elements, etc.), using only the keys they are interested in having printed.

That sounds exactly like the Keywords feature to me. Again with the above, since you have full control over how the keyword list is presented, you can call it “Categories” or whatever you want: