Hello everyone! We at the Diplodoc platform team have read this proposal and found it suitable for our purposes. And now we are actively implementing it into our documentation platform. For this, we created @diplodoc/directive package (it is available in npm). It is based on markdown-it-directive plugin from @lookas (many thanks to him), and allows us to quickly implement new blocks using directive syntax. We find this syntax convenient and are completely satisfied with our choice. Thank you ...