OAS 3.0.0-rc1 Change Log

Schema Changes

url is now required under the Server Object.
Server Variable Object's enum and default values are now string only (were any primitive).
servers under the Path Item Object and Operation Object has been fixed to be an array of Server Objects and not a single one.
The example and examples fields have been reworked, alongside the Example Object. There is no longer examples field under the Schema Object. Where examples exist, they are now a map of named examples with additional metadata for each example. The Example Object now has defined fields and is not free-form.
content is now required under the Request Body Object.
href under the Link Object has been renamed to operationRef, its description is clarified as well.
The deprecated field under the Schema Object now defaults to false.
The flow field under the Security Scheme Object has been renamed to flows.
Request Body's required now defaults to false.
Added allowReserved to the Encoding Property Object.

termsOfService now MUST be in the form of a URL.
all description fields now support CommonMark.
Clarified that specific response codes (200 for example) take precedence over response ranges (2XX for example).
Clarified that for Parameter Object, either schema or content are required.
pattern under the Schema Object now specifies the regex flavor.
Added header restrictions. "Accept", "Content-Type", "Authorization" header paramters and "Content-Type" response headers will now be ignored.
Referenced a specific version of supported CommonMark.
Added clarifications to null not being a type (as opposed to a value).