The format should allow for adding URLs

[WOnder93]

Currently, adding an URL such as https://example.com/url will be interpreted as a key-value pair and something like url:https://example.com/url is also not valid because:

Both key and value must consist of non-whitespace characters, which are not colons. Only one colon separates the key and value.

Being able to refer to URLs is crucial for me (and surely for many others), so I believe the format should allow for it (and make it easy).

[mgiugliano]

I wonder whether free-form annotations (including URLs, colons, etc.) might be added in whatever follows a # symbol, as in a comment for a programming language.