While talking on Progressive non-binary marks for check list?, I extended on some thoughts I had from some time ago, so I better put them in a separate thread here.

The syntax variations on what is not supported by the Djot standard now would require a longer discussion on if what we want is feature completeness or extensibility and if we opt for the second, how to achieve it, without several Djot minor variants that make the format incompatible between variants, repeating the tragedy of the Markdown variants. And to see what is required by the Djot format, we should study the cases where "plain" Markdown was stressed until breaking into variants. Prominent cases of such uses cases are:

• Personal Knowledge Management, with the introduction of internal links, usually with the [[]] syntax and transclusions, using {{ }}.
• Scientific publishing, where Pandoc's Markdown introduced several neededconventions like @ for bibliography management, figure captions and resizing and other additions like the ones reinforced by MyST.
• Interactive documents with variations like the LiveMD introduced by Elixir's Live Book, among others.

So, while advancement indicators in bullet list are a simple case of use, seeing the bigger picture regarding what use cases we want to support so Djot doesn't fracture is an important thing to keep in mind for the format evolution.