A struct used by the Smart Objects system to relay information about the actor attempting to use a smart object. It contains a pointer to the Actor which you can pass as the “user actor” to most Smart Object function calls.
You can extend this struct to pass additional data into Smart Objects. In C++, you can also pass any arbitrary struct into the function calls, but this means you lose the default support for the user actor data, so it’s better to extend this instead.
Extending this struct is supported via Instanced Structs.