UNSPECIFIED

A ViddikScreenshot size that was not given, as opposed to one that was given as a number.

The processor cannot tell "argument omitted" from "argument written out" on its own — KSP hands it the annotation with defaults already substituted — so the default has to be a value no one would write. Without it, falling back to @Preview would be indistinguishable from a fixture that deliberately asked for the old default of 400.