---
title: "Ledger Vocabulary"
description: "Allowed subject classes, identifiers, methods, predicates, and verification states."
canonical: https://y2.dev/docs/ontology/reference/vocabulary/
---

Ontology & Fusion

# Ledger Vocabulary

Allowed subject classes, identifiers, methods, predicates, and verification states.

Values outside these lists are rejected. Terms marked **Y2 profile** add issuer and supply-chain research terms. They use the same evidence, verification, and interval rules.

## Subject classes

| Class          | Examples                                                                    |
| -------------- | --------------------------------------------------------------------------- |
| `person`       | A researcher, an executive, a maintainer                                    |
| `organization` | A company, a vendor, an agency, a threat group identified by its ATT\&CK ID |
| `system`       | A site, a host, a repository, a service, a model, an autonomous system      |

## Designator kinds

| Kind                      | Value                              | Namespace                                                                                                                                      |
| ------------------------- | ---------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------- |
| `published-name`          | The name as the page prints it     | Not used                                                                                                                                       |
| `pseudonym`               | A name sources present as an alias | Not used                                                                                                                                       |
| `handle`                  | The login, without `@`             | Platform or host, such as `github.com`                                                                                                         |
| `email`                   | Lowercase addr-spec                | Not used                                                                                                                                       |
| `url`                     | Exact http(s) URL without userinfo | Not used                                                                                                                                       |
| `domain`, `hostname`      | Lowercase host, no trailing dot    | Not used                                                                                                                                       |
| `asn`                     | `AS` and a decimal number          | Not used                                                                                                                                       |
| `public-key`              | Lowercase hex fingerprint          | Algorithm, such as `ssh-ed25519`                                                                                                               |
| `external-id`             | A registry identifier              | `wikidata` (`Q…`), `lei` (20 characters with valid check digits), `attack-group` (`G` and four digits), `sec-cik` (ten digits, **Y2 profile**) |
| `ticker` (**Y2 profile**) | Uppercase listed symbol            | ISO 10383 exchange MIC, such as `XNAS`                                                                                                         |

## Observation methods

`public-web-page`, `public-profile`, `public-dns`, `certificate-transparency`, `public-archive`, `public-registry`, `public-code-host`, and `analyst-note`.

Authenticated access, non-public access, and interaction with the subject are not supported observation methods.

## Predicates

| Predicate                        | From                   | To                        | Meaning                                                       |
| -------------------------------- | ---------------------- | ------------------------- | ------------------------------------------------------------- |
| `designated-by`                  | subject                | designator                | The subject is referred to by this identifier                 |
| `preferred-label`                | subject                | name designator           | Display this name. Requires a live `designated-by`.           |
| `same-as`                        | subject                | subject of the same class | Hypothesis that the rows are one entity                       |
| `distinct-from`                  | subject                | subject of the same class | Hypothesis that they are not                                  |
| `member-of`                      | person                 | organization              | A public role, in `qualifier`                                 |
| `affiliated-with`                | subject                | subject                   | A weaker public tie                                           |
| `controls`                       | person or organization | system or designator      | Claimed control, supported by a source that addresses control |
| `operates`                       | person or organization | system                    | A source says this party runs that system                     |
| `resolves-to`                    | designator             | designator                | A public resolution for the interval observed                 |
| `follows`                        | handle                 | handle                    | A public page shows one account following another             |
| `supplies` (**Y2 profile**)      | organization           | organization              | The first supplies goods or services to the second            |
| `subsidiary-of` (**Y2 profile**) | organization           | organization              | The first is owned or controlled by the second                |

`same-as` and `distinct-from` never merge rows. When both are live for a pair, the pair is contested.

## Verification ladder

Verification belongs to a claim, not to a subject.

| State           | Honest use                                   | Evidence the ledger requires      |
| --------------- | -------------------------------------------- | --------------------------------- |
| `unverified`    | Written down, not checked                    | At least one observation          |
| `mentioned`     | The string appeared without a supported link | A public retrieval                |
| `located`       | One retrieved page ties them                 | A public retrieval                |
| `self-asserted` | The subject's own page states it             | A public retrieval                |
| `cross-linked`  | Two retrieved pages identify the link        | Retrievals of two different pages |
| `corroborated`  | A further independent source agrees          | Retrievals of two different pages |
| `contradicted`  | A source disputes the link                   | A public retrieval                |
| `stale`         | The page is gone or no longer shows it       | A public retrieval                |
| `analytic`      | The only support is an analyst note          | Only analyst notes                |

A claim supported only by notes is `analytic` or `unverified`.

## Source grades

| Grade       | Meaning                                                           |
| ----------- | ----------------------------------------------------------------- |
| `primary`   | A direct source, such as a profile, staff page, or registry entry |
| `secondary` | The page reports on the thing                                     |
| `analytic`  | An analyst note that cites the observations it connects           |