x-apim-request-id
`x-apim-request-id` appears on header objects. Its value is a string. Used by a single provider across 2 OpenAPI documents. Observed values include `a1b2c3d4-e5f6-7890-abcd-ef1234567890`, `b2c3d4e5-f6a7-8901-bcde-f12345678901`, `c3d4e5f6-a7b8-9012-cdef-123456789012`, `d4e5f6a7-b8c9-0123-defa-234567890123`. Consistent with identity & relationships — 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 | |
|---|---|---|
| header | 7 | |
| schema | 2 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| string | 7 |
| object | 2 |
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.