Can we please have a place where changes to the markdown syntax are documented?

Question

As I have observed in two recent questions, there's been some recent change to the syntax for inline code in comments. Let me here document the changes I found out so far (as in found out the hard way):

1. A backtick must now always be escaped. Until recently, ``` gave `, and `\catcode`A=\active` gave \catcode`A=\active; one didn't have to escape backticks before letters.

2. updated Update: Related to the 2nd part of #1: Now you can have a letter immediately after the closing backtick, so that you can have e.g. "<br>s" in a comment. But this only works if you also have <br> in the comment.

3. There's no backslash escaping for (, ), [, ], * and _ anymore.

4. You mustn't have spaces in the beginning of the inline code.

While I'm perfectly happy with these changes per se, I have two problems:

1. They affect the old comments as well, making them distorted in some cases. (Jeff has corrected this on (meta.)tex.sx, except for the 2nd part of #1 above; thanks a lot!)

2. Those changes happened without any notice or explanation.

Thus my feature-request: Can we please have some place where one can look up all changes of this sort? And in the future, as there are more changes to come, wouldn't it make sense to leave the rendering of old comment untouched?

(I have no way of knowing if my list above is complete, so I'd really like to know what exactly the recent changes were. Sorry that I keep bumping this post, but I'm still discovering new kind of behaviour unknown to me before. Which may underpin the point I'm making.)

Answer 1

Bold & Italic

This now works as expected:

Let me ***emphasize*** this

turns into

Let me emphasize this

Codeblocks in multiple backticks

This is new, and almost works like in regular markdown now:

```code with one ` or two `` backticks```

becomes

code with one ` or two `` backticks

There is no escaping at all in multi-backtick code. Start a code block with five backticks, and everything will appear verbatim until we find another run of (precisely) five backticks.

Codeblocks in single backticks

This behaves like it previously did, and is a slight deviation from the Markdown spec: If the codeblock is enclosed in single backticks, you can escape a backtick (and only a backtick) with a backslash.

`code with one \` or two \`\` backticks`

gives the same result as above.

All codeblocks

As you noticed, codeblocks cannot start with whitespace anymore. In particular, this means if you want a backtick to appear as the first character, you have to use this variant:

see: `\` <- that is a backtick`

becomes

see: ` <- that is a backtick

Another change is this: We now use the same rules as proper Markdown when it comes to ending codeblocks. When you start a code block with n backticks, this code block is ended the first time we find another run of n backticks, no matter what comes. This especially means that the following now works:

There aren't enough `<blink>`s in your page.

turns into

There aren't enough <blink>s in your page.

Magic links

Some sequences of the form [word] are converted to hyperlinks, for example [faq] links to the site's FAQ (e.g. https://meta.stackoverflow.com/faq), etc. See Add data.SE style “magic links” to comments for the full list.