[cells-devel] laziness -- what does "once-asked" mean?

[Larry Clapp]

I understand (I think ...) what :once-asked *does*, I want to know
what it *means*.

In other words, the other two options seem to answer the question
"when is this cell lazy?"  Well, an :always cell is always lazy --
it's not recalculated until and unless you ask for it.  An
:until-asked cell is lazy until you query it once, then it's non-lazy
from then on.

"once-asked" seems to answer a *different* question, "when is this
cell evaluated?"  It's evaluated once, when created, and then only
when queried.

Is there any single "question" that all three answer, or are they just
inconsistent?

Thanks!

-- L