Data & schema semantics · Validation & constraints

x-cel-rule-0

`x-cel-rule-0` appears on schema objects and properties. Its value is a string. Used by a single provider across 10 OpenAPI documents. Observed values include `self == oldSelf`, `!oldSelf.hasValue() || self == oldSelf.value()`, `self.size() == 0 || isIP(self)`, `self >= oldSelf`. Consistent with validation & constraints — this is inferred from where the key appears and what it carries, not from any published definition.

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.

70 occurrences

10 documents

1 providers

purpose-named

Where it appears

Location in the document	Occurrences
schema	70

What its value looks like

Value shape	Occurrences
string	70

Observed values

Sampled from the specifications, most frequent first.

self == oldSelf!oldSelf.hasValue() || self == oldSelf.value()self.size() == 0 || isIP(self)self >= oldSelfself.size() == 0 || (isCIDR(self) && cidr(self).ip().family() == 4)self.size() == 0 || (isCIDR(self) && cidr(self).ip().family() == 6)self.all(x, isIP(x))!has(self.from) || !has(self.to) || self.to >= self.from

Providers publishing it

All 1.

eu-sovereign-cloud-api

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.