Your quotation and list syntax should work out of the box in most Markdown flavors (HN has a very non-standard and crippled version - basically nothing other than italics, paragraphs, and code/preformatting works.)

Strikethrough and bold are doubled to avoid common ambiguities. Your underline should technically work, but it comes out as an <em> (emphasis) tag, which is rendered as italics in most browsers.

I have long used underscores for _emphasis_, but I never made the connection that it was meant to resemble an underline until now.

One problem with the /italics/ form is that it's not convenient when writing about filesystem paths (though I do like its visual indication of slanting).

Yeah, *asterisks* for italic has always felt wrong to me. I can understand underscores if slashes cause confusion with file paths.

*bold* and _italic_ would have been better.

Thanks for posting this. I feel like for years we've been getting gaslit by the Markdown guys who inexplicably decided that stars should make text go italic instead of bold. I get it wrong every single time and then have to go back and look up a cheat sheet. It really isn't intuitive at all, and it also doesn't codify how we used to write before rich text entry boxes where available everywhere. Markdown reminds me more of all the custom wiki and forum markups that proliferated in the 2000s than any text-based conventions in use prior.

I have historically used asterisks for emphasis and slashes for the use/mention distinction.

Org-mode FTW

But Usenet style didn't have a trendy name, an 'inventor' or Github stars. So it didn't exist.