VK_FORMAT_G12X4_B12X4R12X4_2PLANE_422_UNORM_3PACK16

Undocumented in source but is binding to an external library. You might be able to learn more by searching the web for its name.
nothrow @nogc extern (System)
enum VK_FORMAT_G12X4_B12X4R12X4_2PLANE_422_UNORM_3PACK16 = VkFormat.VK_FORMAT_G12X4_B12X4R12X4_2PLANE_422_UNORM_3PACK16;

Meta