this uses the STEM asciidoc extension https://docs.asciidoctor.org/asciidoctor/latest/stem/ which is defined in the asciidoc spec.

some event kinds use asciidoc for their content (30041 in the example) so they might use extensions. clients that don't support STEM extension will simply ignore those blocks or show it as plain text.

the client is chachi.chat :Chachi: