## Description

Provisional extensions should not be used in production applications. The functionality defined by such extensions may change in ways that break backwards compatibility between revisions, and before final release of a non-provisional version of that extension.

Provisional extensions are defined in a separate provisional header, vulkan_beta.h, allowing applications to decide whether or not to include them. The mechanism is similar to window system-specific headers: before including vulkan_beta.h, applications must include {core_header}.

 Note Sometimes a provisional extension will include a subset of its interfaces in {core_header}. This may occur if the provisional extension is promoted from an existing vendor or EXT extension and some of the existing interfaces are defined as aliases of the provisional extension interfaces. All other interfaces of that provisional extension which are not aliased will be included in vulkan_beta.h.

As a convenience for applications, {full_header} conditionally includes vulkan_beta.h. Applications can control inclusion of vulkan_beta.h by #defining the macro VK_ENABLE_BETA_EXTENSIONS before including {full_header}.

 Note Starting in version 1.2.171 of the Specification, all provisional enumerants are protected by the macro VK_ENABLE_BETA_EXTENSIONS. Applications needing to use provisional extensions must always define this macro, even if they are explicitly including vulkan_beta.h. This is a minor change to behavior, affecting only provisional extensions.
 Note This section describes the purpose of the provisional header independently of the specific provisional extensions which are contained in that header at any given time. The extension appendices for provisional extensions note their provisional status, and link back to this section for more information. Provisional extensions are intended to provide early access for bleeding-edge developers, with the understanding that extension interfaces may change in response to developer feedback. Provisional extensions are very likely to eventually be updated and released as non-provisional extensions, but there is no guarantee this will happen, or how long it will take if it does happen.