What does it mean when a book is "In Transit"?

When a regular book in the catalog says "In Transit" it is most likely coming back from or going to one of the 4-Colleges. If it is a regular book in our collection and it is going to one of the 4-College because of someone's request it may not be back for a couple of weeks and the patron you are speaking with may want to find the book somewhere else. Unfortunately there is no way to know in which direction the book is going.