x-amz-date
`x-amz-date` appears on schema objects and properties and on response objects. Its value is a structured object. Used by 6 providers across 6 OpenAPI documents. It sits in the `x-amz-` namespace, so its meaning is defined by amz tooling rather than by OpenAPI. Consistent with units & formatting — 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 | 5 | |
| response | 3 | |
| operation | 1 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| object | 5 |
| string | 4 |
Observed values
Sampled from the specifications, most frequent first.
Providers publishing it
All 6.
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.