OAS 3.0.0-rc2 Change Log

Schema Changes

The following objects have been removed from the specification: Server Variables, Content, Encoding, Callbacks, Headers, Links, Link Parameters, Scopes. They have all been replaced by the Map construct being effectively what they are. Clarifies that specification extensions are not allowed, as they did not make sense.
The Encoding Property Object has been renamed to the Encoding Object. This is a result of the above change.
The Encoding Object now specifies to which media type each property is applicable.
The Encoding Object now defines headers as a map of Header Objects.
The different components under the Components Object can now either be defined inline or referenced.
For parameters using content, now only one media type can be used at most.
The headers property under the Link Object has been removed.
Link Object has a new requestBody property to allow passing a request body.
The Schema Object's discriminator property has been completely reworked to utilize the newly supported oneOf and anyOf. A new Discriminator Object has been added to support these changes.
The XML Object's namespace now MUST be an absolute URI.
The apiKey security scheme can now also be in cookie.

The Rich Text Formatting section has been reworded to ease the requirements.
Added OpenAPI Definition File definition.
Clarified that an empty or nonexisting servers would default to a single Server with the url value of /.
Reworded the section explaining the specification's versioning scheme.
Server Variable enum's description has been fixed to state it can only be a string (the type was correct).
Added clarification + examples how path matching works for paths defined under the Paths Object.
Removed recommendation for a 120 character limit for the summary field under the Operation Object.
Further details added to the form and simple types of style.
Clarified that the Encoding Object applies to both multipart and application/x-www-form-urlencoded and only those.
Clarified the possible response code wildcards are only 1XX, 2XX, 3XX, 4XX or 5XX.
Variable Expressions have been renamed to Runtime Expressions. They have been unified between Links and Callbacks, and have a dedicated section. Various examples have been moved and removed as a result.
Runtime expressions now use curly braces when found inside strings.
Link Object's parameters now defines how to deal with cases of parameter name ambiguity.