Chris Aldrich’s feed pointed me to this resource on Personal Knowledge Graphs (which he co-authors/-ed). In it Martynas Jusevičius mentions as an issue with markdown being used for personal knowledge graphs is their incompatibility with the RDF ecosystem as there is no support for typed links in markdown. I disagree with the statement that that would turn markdown knowledge collections into a ‘walled garden’. There’s no garden there. It does hinder interoperability with more complex environments like RDF / semantic web, and potential connections and interactions with other graphs and people.

A question I think is whether the burden of arranging interoperability lies with the least complex or with the most complex part. Probably the latter, which points away from plaintext and markdown, to at least having a parser that adds the additional complexity. Markdown always needs a parser, it’s not intended for other people to see other than the author(s).

On the other hand, being able to characterise links sounds like at least a somewhat doable step in a markdown text environment. In terms of publishing such notes to my blog that should translate into microformats in html, but parsing it to xml is a similar step.

A quick search came up with this post ‘Semantic Markdown‘.
It shows the issue of adding more complexity to markdown well I think. As an authoring tool you don’t want to make writing more complicated, nor make reading back what you’ve written less easy for human eyes. This is why I e.g. generally avoid frontmatter in my markdown notes in Obsidian, as it reduces the ease of reading for myself. Inline data fields used sparingly are less disruptive to me.

The article also provides imo mostly unconvincing examples, like labeling Berlin as a geographic place, or an event name as an event. Especially given the effort involved marking them up as city or event. I’d like to form more meaningful triples around external links (a reply to b, a part of b), also between notes (‘a counterexample of b’) where the information is in the type of relationship between two points. There’s some association here with one OPML file embedding other OPML outlines by pointing to them, and the branching in a classic Zettelkasten or even code repo’s.
Don’t want to just add links to mundane things (this word refers to a city): I e.g. dislike a lot of Wikipedia links inside Wikipedia lemma’s where they link to the lemma of a thing in general, but not to its meaning within the context of the link placement, while the phrasing suggests the link will provide more context. That’s just like adding every single word in a sentence to its dictionary page to me.

In the comments underneath that Semantic Markdown link, similar things are mentioned, alongside links to a semantic markup language bridging xml and markdown, and another one describing the same.

(I’m not sure what this type of post is, I find myself writing several in parallel yesterday and today, triggered by reading streams of public annotations. I’ve dubbed it Jottings. It’s an attempt at blogging something in the stage between just bookmarking a url with some motivation and something more well formed based on an actual experience or exploration. More grasping at first connections, less formed opinion, but also not just annotation as it is rather somewhat removed from the source text and not anchored to it. More holding questions than providing insights or answers.)