VK_FORMAT_R64G64B64A64_SINT

Undocumented in source but is binding to an external library. You might be able to learn more by searching the web for its name.
@nogc nothrow extern (System)
enum VK_FORMAT_R64G64B64A64_SINT = VkFormat.VK_FORMAT_R64G64B64A64_SINT;

Meta