x-obmcs-top-level-enum
`x-obmcs-top-level-enum` appears on schema objects and properties. Its value is a string. Used by a single provider across 122 OpenAPI documents. It sits in the `x-obmcs-` namespace, so its meaning is defined by obmcs tooling rather than by OpenAPI. Observed values include `#/definitions/LifecycleState`, `#/definitions/OperationStatus`, `#/definitions/OperationType`, `#/definitions/SortOrder`. Consistent with type system — this is inferred from where the key appears and what it carries, not from any published definition.
Where it appears
| Location in the document | Occurrences | |
|---|---|---|
| schema | 3360 | |
| parameter | 664 | |
| other | 5 | |
| operation | 4 | |
| header | 6 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| string | 4039 |
Observed values
Sampled from the specifications, most frequent first.
Providers publishing it
All 1.
Why this is not in OpenAPI
Extensions exist because a provider needed something the specification would not carry. Most of what they hold is not the API contract at all — it is operational metadata about the contract: documentation, lifecycle, policy, provenance, and now agents. That metadata is usually better placed alongside the contract, in an Overlay or an APIs.json index, than crammed inside it. See everything else doing the data & schema semantics job.