Q. What does it mean that a book is In Transit?

In Transit mean the item is on its way from one library to the other, either to return to its home library, or because it is on the way to fulfill a hold.  You can place items that area In Transit on hold, but they may not be available for a few days.

Tech TO Update and Tech NP Update mean the item is being repaired or replaced due to damage or loss.  You can place a hold on an item being updated, repaired or replaced, but it may take some time before the item becomes available again.