I was under the impression that the Gruber original at https://daringfireball.net/projects/markdown/ wasn’t well enough specified (unless you want to treat a 20 year old Perl script as a specification) to be interoperable - hence efforts like https://commonmark.org/

So it's whatever you care to specify. Doesn't have to be Markdown at all. It looks like it'd be completely valid to use this as a way to bundle up a webpage with all associated images and scripts, for instance.

Anyone else's flavor of Markdown can be used by specifying its identifier, e.g. "com.github.markdown.v3" (I made that up, it's not a real thing AFAIK)

I like the general concept of sandboxing applications, but if it leads to this, it's more hindering than helping.

In particular, if you attach a file to a note in obsidian then no other program can link to the right attachment, right?

Your directory has note.md and image.jpg. The note has a link to the image. The client can then render the markdown and image as it wants.

Any other application can also find and link to the attachment because...it's a file.

Most recently I tested this with obsidian, ia writer, obsidian.nvim, fsnotes, and a few others I forget the name of.

Especially if you want to access your notes on mobile and have a good syncing experience... you're out of luck if you want a non-proprietary format. Only notion and apple notes had reliable syncing.

Sure, I can zip everything and send them over, but it's not as friendly for recepient as receiving a document handled by popular viewers, specially if they have to modify it and send it back.

With wide adoption of something like TextBundle, we get to have our cake (keep using plain text) and eat it too (send, view, and edit richer files).

solves this one issue at least

I use markdown for personal notes and in the rare case I shared them in the past, either there were no (relevant) links or I shared with e.g. confluence and I could just add the image.

My other usecase for markdown is Readmes and those are shared in git including the files.

I understood this spec mostly for sharing with local apps. Is that a missed usecase by me? Markdown documents instead of word/pdf/powerpoint/whatnot?

Personally, I was hoping TextBundle would be something like a standard format for inserting binary content into Markdown files. (Something better than just base64, anywho.) I could use such a thing for my home-grown wiki.

Oddly enough, I was recently thinking of using RFC 822 messages with CommonMark bodies and MIME attachments as a way to store blog entries on disk, so I was considering this exact problem earlier this week (small world!). RFC 2046 specifies multipart messages, RFC 2392 specifies URI schemes for linking from the body of the message to other parts; and RFC 7763 specifies the text/markdown MIME type. There’s already a ton of tooling out there which deals with MIME, so one needn’t reinvent the wheel.

... So basically a markdown version of the ePub format?

Slightly related, but Typora offers an option that handles inlined media for a markdown note in a pretty sleek way. It creates a folder in the same location as the markdown note with following syntax (markdown-file-name.assets). Any time you drag/copy/etc a image/video/etc into the markdown editor it copies the file into the asset folder.

Surely with Pandoc and macOS/iOS progressing relentlessly, there would be some technical advances even in a basic file bundle.