What it speaks
This page is the authority. Everything outward-facing must agree with it, and it must agree with the code. If they ever disagree, the code wins and this page is the bug.
Nothing is described as supported until an implementation exists and a real client has driven it. The right-hand column is what that rule looks like when it is being kept.
PROTOCOL STATUS VERIFIED BY Gemini supported gemini-diagnostics, Lagrange Titan supported Lagrange Web supported browsers, lynx, w3m Gopher supported gelim, against a live public deployment Spartan supported Lagrange, rendered live Nex supported gelim Finger supported bombadillo anything rejected answered 53; this is not a proxy else
What "verified by" means
A protocol is called supported when it has been exercised against a real client, not merely unit-tested. All of them have been.
Spartan was hedged until the hedge could be lifted honestly. One client's Spartan mode returned nothing in non-interactive use, and returned nothing against the reference server either, so it was a client limitation rather than a defect here. Rather than round that up, this page said "wire-verified" and named the gap until Lagrange rendered it live.
That comparison also produced a fix worth keeping on record. The reference server answers with a bare content type; this one had been sending a charset parameter too. UTF-8 is already the default for text, so the parameter added nothing and gave a client doing exact string comparison something extra to disagree with. Now matched.
The web mirror is not a web server
Your content tree is rendered to static HTML and that is served. Nothing is executed, there is no CGI, and it will not reverse-proxy. If you need a general-purpose web server, run one. This surface exists so writing is also readable by someone who only has a browser, from the same source files, with no second publishing step.
The cleartext protocols carry less
Gopher, Spartan, Nex and Finger offer no confidentiality, no integrity, no server authentication, and no client authentication of any kind. Certificate-gated and upload-gated paths are therefore excluded from every cleartext tree, structurally, at the point the tree is built. All four are off unless the operator enables them.
Choosing between them, with the case for each
Why that exclusion is structural rather than a check
Per-capsule versus per-project
This page answers "what can the software speak?": a question about the software.
"What does this site answer on?" is a different question with a different answer per install, and it should never be maintained by hand. Only the running server knows. That answer is generated, at /usv, from live configuration: true by construction and incapable of overclaiming.