I love this.

> Having both begin and terminate arrays start with << is more consistent.

It hides context for humans. I am a human and I love to see what opens and what closes the context. Why would `<` open an array if `[` is astonishingly wide-spread practice? Why would `<<` close it just because you think it is more consistent? What if open/close balance is also consistency, especially for nested arrays?

Also just think how many key strokes you'd save if you'd use `]` instead of [Shift]+`,` [Shift]+`,` [Shift]+`4` [Shift]+`.` if you declare it as readable text.

> Using `{` and `}` would lead to more special characters.

Agree. Too many now.

> It is simpler to support graphs in the markup. The fact is that the data being serialized may be structured in a graph.

I can't understand why you call it native graph support. The only thing it does is declaring an identified element and references to the element. I can't see how different is that comparing to XML or JSON that semantically "have graph support" just because they also can declare something considered ids and references to the identified element.

> LaTex and PostScript both use % for comments.

Yes, just learnt that from your comment and https://news.ycombinator.com/item?id=42047634 by zzo38computer. Thank you.

> # matches the usage in ᴄꜱꜱ and ʜᴛᴍʟ, relating to an id/page location.

No. The # symbol is overloaded: it may be a comment start, especially for line-oriented and human-readable text formats or scripts; CSS uses it for IDs; HTML has nothing to do with it since browsers only use # as a part of a URL to reference a particular identified element for navigation purposes only (it's called anchor in URL syntax; formerly web-browsers used <a name="anchor"> to navigate to a part of the page; as of now in the HTML5 world any `id` attribute is considered an anchor which I find a design flaw since ids are something to be used to identify hence any id from the document is exposed for navigation navigation purposes, but <a name="anchor"> is semantically something for navigation).

> Having a space after the # differentiate between and id and comment would be a mistake.

Of course it would in its current perspective if the id declaration is `#`. Don't know what `#<NON_WHITESPACE_CHAR>` would do if it's legal.

> The Formats section is to facilitate interoperability between implementations, e.g. if you are encoding a ɢᴜɪᴅ [easy to say] then format it this way.

I agree that it may look better for consistency purposes, but what interoperability is all that about? Why would formatting even affect it? From the consumer application point of view, it must be handled from its context defined by its purpose and semantic type. If my element/attribute is formally declared as a GUID, then why would I care that much if it's conventionally formatted? Would it be still a GUID if I encode it using Base64? The dashes in GUIDs are for humans only and they are optional, and the application knows it's a GUID to process it even leniently if it can. The same goes for ISBN/ISSN for books and magazines, card numbers, phone numbers, etc -- none of them require dashes or spaces or parentheses to be processed.

This is why "Real numbers *should be stored* with commas for readability." is just hilarious. Why should? May I use underscores or dots or spaces to group digits (seriously, why comma)? Can I group digits after the period? If I need integers, why are they also limited to 32 bits and 64 bits? How would I present an arbitrary precision integer or non-integer number (say, I want the Pi number 197 digits after the 3)? If ∞ is allowed, but no mention on +Inf and -Inf, can be 4.2957×10^24 used instead of 4.2957e24? May I just have simple `D+(\.D+)?` for everything I need for true interoperability?

I agree consistent formatting is really beautiful, but it must never be the key to process data.

> It is more terse than ᴊꜱᴏɴ.

Sorry, it's not.

> Good

Could you please provide an example of minified (a single line, no new lines) array of timestamps from your page?

UPD: I've just seen https://news.ycombinator.com/item?id=42038508 by Oras . Well, you know.

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In short, too many whys, weird syntax and design decisions, so I cannot see anything that makes it a "better alternative" to XML, JSON, or YAML.