[Digit-Al]

"\v" is an ASCII control character, and means "vertical tab" (VT). In ASCII it is code 11, which is why they are inserting the number 11.

[turtleyacht]

Yes. In this case, it represents "teaching" the compiler something it didn't previously "know" about. But wanted to connect that to whether the computed output of a language could ever be falsifiable, i.e. we would not know it happened.