Today, In Tizen developer related news, it has been announced that the Tizen 2.3.1 Software Development Kit (SDK) will no longer be supported after April 1st 2016. When this specific SDK was released it would only support version 2.3 and 2.3.1 of the Tizen Operating System (OS).
Now, with the release of the Tizen 2.4 SDK, all the features of Tizen 2.3.1 platform as well as Tizen 2.4 platform are contained in one SDK. Developers need to only use this one SDK to develop their apps for both Tizen 2.3.1 and Tizen 2.4 platforms.
You can find the current released version of Tizen 2.4 Rev 4 here.