The day of the last live check by this package's maintainers (YYYY-MM-DD), or null.
When the registry last fetched the endpoint (ISO 8601); null for curated entries.
A short note, e.g. that the server is an archive or needs a certificate workaround.
"1.0", "1.1", … taken from the System's oparlVersion; null when unknown.
Why that check failed (e.g. "HTTP 404"), or null.
The System URL that replaces this one, when the server moved.
Where the entry comes from: the dev.oparl.org registry or the curated list.
The System's name (usually the product), when known.
The endpoint's System URL.
Whether the endpoint answered with a System and its bodies: from the most recent
live check (checked) when there is one, else from the registry's last fetch.
An OParl endpoint as
endpoints()lists it: an entry of the public registry at dev.oparl.org, or of the curated list shipped with this package.