Data & schema semantics

x-xgen-version

`x-xgen-version` appears on response objects. Its value is a string. Used by a single provider across 1 OpenAPI document. It sits in the `x-xgen-` namespace, so its meaning is defined by xgen tooling rather than by OpenAPI. Observed values include `2023-01-01`, `2024-08-05`, `2024-05-30`, `2023-02-01`. Consistent with data & schema semantics — this is inferred from where the key appears and what it carries, not from any published definition.

Data & schema semantics x-xgen- namespace derived description
How this description was produced. It is assembled from what was measured in the corpus — where this key appears in a document, what shape its value takes, the values observed, and how many providers use it. It is not taken from a published definition, because for most extensions none exists. Read it as evidence, not as a specification. If you own this extension and want it described properly, tell us.
502 occurrences
1 documents
1 providers
vendor-named

Where it appears

Location in the documentOccurrences
response 477
requestBody 22
operation 3

What its value looks like

Value shapeOccurrences
string502

Observed values

Sampled from the specifications, most frequent first.

2023-01-012024-08-052024-05-302023-02-012025-03-122024-11-132023-11-152025-02-19

Providers publishing it

All 1.

mongodb

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.