Data & schema semantics · Validation & constraints

x-validation-message

`x-validation-message` appears on schema objects and properties. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `must be a valid GTM container ID (format: GTM-XXXXXX)`, `must be a valid Google Analytics ID (format: G-XXXXXXX)`, `must be a data URL with base64 PNG image data, e.g., data:image/png;base64,

Data & schema semantics 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.
10 occurrences
1 documents
1 providers
purpose-named

Where it appears

Location in the documentOccurrences
schema 10

What its value looks like

Value shapeOccurrences
string10

Observed values

Sampled from the specifications, most frequent first.

must be a valid GTM container ID (format: GTM-XXXXXX)must be a valid Google Analytics ID (format: G-XXXXXXX)must be a data URL with base64 PNG image data, e.g., data:image/png;base64,must be a data URL with base64 JPEG image data, e.g., data:image/jpeg;base64,must be a data URL with base64 SVG image data, e.g., data:image/svg\+xml;base64,must be a data URL with base64 GIF image data, e.g., data:image/gif;base64,must be a data URL with base64 ICO image data, e.g., data:image/ico;base64,must be a valid hex color value

Providers publishing it

All 1.

kong

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.