The hierarchy
Roots are tags too. The top-level subjects head the tree for browsing, and a document about a subject in general carries the root alone. A tag applied to an RFC implies its whole path, so a parent's count includes its children; the root row's bar is the whole subject.
Topics are subjects and cross-cutting aspects, set in violet in the text face; technologies are named protocols, systems and formats, set in the RFC series' own typewriter face. Roots are always topics. Search matches tag names and descriptions on whole words. Two measures, kept apart: Corpus is how many RFCs carry a tag; mail/yr is how many notifications a subscriber would have received per year since January 2021. When they disagree, the disagreement is the finding.
Selection
Pick a tag on the left. You will get its place in the tree, its kind and definition, the tags it travels with, and the RFCs themselves by number and title.
Tags that travel together
Every pair of tags directly assigned to the same RFC. A pair near the top that also sounds like one idea is a merge candidate; a tag that appears only inside pairs never stands on its own. Pairs where one tag is the other's ancestor are marked kin: the tree already states that relationship. Raise the threshold to cut the tail.
When each tag was in use
First to last RFC carrying the tag, across 1968–2026, newest last use first. Blue means the tag has been used since 2021 and would still notify someone; rust means nothing has carried it in over a decade; grey is in between. A vocabulary for subscription should be mostly blue, and the rust rows are the ones to weigh: a finished protocol still deserves a search tag, but not a subscription.
Tags assigned to the same RFCs
Two different measures, because they mean different things. Two-way overlap (Jaccard, shared ÷ combined) high in both directions says two tags are doing one job — a redundancy candidate. One-way overlap (containment) high in one direction and low in the other says one tag sits inside the other — a broader/narrower candidate the tree does not yet record. Pairs already related as ancestor and descendant are excluded.
A third possibility is worth naming, because it looks like the second. High containment can mean the tags are genuinely nested, or it can mean a match rule in taxonomy.yaml is over-firing. Read the shared RFCs before concluding the vocabulary is at fault — the fix may belong in the rule table instead.
Assignments to look at
The engine records why an assignment might be wrong: the tags came from the abstract because nothing else matched; a technology rests on author keywords alone; a root sits beside a technology from another subtree; the document carries eight or more leaf tags; this is the first document to carry a tag; or the document shares no tag with the RFC that obsoletes it. A document with none of these is not thereby right, only unremarkable. A document with an entry in assignments.yaml has been reviewed by a person and is not listed. This page shows the queue; the review itself is recorded in that file.
| RFC | Year | Title | Tags | Why |
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Every published RFC and its tags
All 9,835, newest first. Type a number to jump straight to one — 8446, rfc 1149 — or type words to search titles. Tags are clickable: any of them takes you to that tag in the hierarchy. A single RFC also shows its served coordinates: the technology tags it carries and the topics they imply.
| RFC | Year | Title | Tags |
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