Hmmm. No you haven't. You have noted one of the circumstances in which
a mark becomes active, yet haven't said what it is for a mark to BE
active. It is as though a young child has asked you what "pregnant"
means, and the entire gist of your answer is "a woman becomes pregnant
after a kissing and cuddling session". Unless you mention the growing
foetus, your answer is evasive and unhelpful, in fact not really an
answer at all. What, exactly, is the essence of "active"ness, in the
same way that the foetus is the essence of pregnancy?
The problkem is that the activeness of the mark doesn't describe some
property of some other state. It's a state itself. In your analogy,
there's no foetus that would allow us to determine whether the mark
is active. All we have is the `mark-active' variable, so in the end all
we can say is "the mark is active if the mark is active".