Alice casts Unexpectedly Absent with x = 4 on a Atog.
After that resolves Nalini casts Dig Through Time.

While Dig Through Time is resolving, does Nalini need to indicate which of the seven cards she chooses? That is, will Alice know whether the Absent Atog was among the cards chosen?

Alice will clearly not know the order of the five cards that go on the bottom.

I think that Nalini cannot re-order the cards as she is choosing from among them, due to
401.2. Each library must be kept in a single face-down pile. Players can't look at or change the order of cards in a library.
and
101.4a. If an effect has each player choose a card in a hidden zone, such as his or her hand or library, those cards may remain face down as they're chosen. However, each player must clearly indicate which face-down card he or she is choosing. <edit> 101.4a doesn't apply, since it's referring to what to do when each player chooses, not when A player chooses.

So even though it's a private zone she still has to maintain the order until after the two cards are chosen. And if she does not need to reveal which cards she selects (that is, cards 2&3, for example, obviously she does not need to reveal the face of the cards), how does she reasonably hide her selection without reordering them?

Edited Joshua Kimbrough (Oct. 3, 2014 01:38:27 PM)

This is the same question as the Courser of Kruphix/Dig Through Time question from yesterday, and the same answer applies: Alini is not entitled to know whether or not the Atog was among the cards put into Nalini's hand. How Nalini might reasonably hide her selection is up to her; the practical limitations of playing a game using physical objects sometimes means that your opponent is going to be able to infer more information than the rules would hand out on their own. If you draw a card and drop a land for the turn, a sharp-eyed opponent may be able to spot whether or not the land was the card you drew, even though the rules don't provide them with that information.

However, keep in mind that 101.4 is there for cards like Show and Tell; it's to ensure that the player clearly indicates which pieces of cardboard they're choosing at the appropriate time, rather than keeping things ambiguous until their opponent reveals their choice and making their real selection later based on that information they weren't supposed to have when choosing. It's not intended to combine with the ordered nature of the library to force you to tell your opponent just how many cards down that basic land you found with Rampant Growth was.

We don't stop players who resolve Rampant Growth from rearranging their library while they search even though strictly speaking the rules don't allow them to do it. Forcing them to maintain the order is tedious and time-consuming, and since it's immediately followed by a shuffle it only ever matters in ridiculously artificial situations involving cards nobody plays. The same logic applies to effects like Dig Through Time and scry. Let Nalini rearrange her cards as she wishes; she's about to put them on the bottom in an order of her own choosing anyway.