If only the basic Uru: Ages Beyond Myst (ABM) is installed, then your left bookshelf at Relto - at your island hoovering in the sky - is empty. If the first expansion pack (To D'ni) is installed you will see the Neighborhood Book. If the second expansion pack is also installed (The Path of the Shell, TPOTS, or the second disc of Complete Chronicles), then the linking Book to the Watcher's Pub is also on the shelf. In the case of the online Until Uru (UU) some of the Books may contain more additional links.
As you advance in the game you'll have more and more books on the shelf.
The clips found at the top of the Books can be turned up - this is significant only in the online game Untěl Uru (to allow the visitors to use or not your Books). By clicking the clip at the bottom edge of the Books they will be reset (and the puzzles in that Age as well). The Book of the Desert (Earth and Tomahna). It is available only if your mission in the five basic Ages is fulfilled. The Book of Gahreesen, leading to the Age of Maintainers with the rotating fortresses. One of the five basic Ages. The Book of Teledahn, the Age of the giant mushrooms. One of the five basic Ages. The Book of Kadish Tolesa, the Age of the giant trees and puzzles of Master Kadish. One of the five basic Ages. The Book of Eder Gira, the Age of fumaroles and lava flows. One of the five basic Ages. The Book of Eder Kemo or the Garden Age. One of the five basic Ages. The City Book. The links to the city are collected to this brown Book. On using a Bahro stone (linking stone) the first time, the appropriate link is added to this Book and that place can be reached later directly via this Book. In ABM only isolated, closed parts of the city (balconies etc.) can be reached this way. The Neighborhood Book. Links directly to your Neighborhood. If only ABM is installed, only a balcony is available. The Nexus Book links to a tiny Age, different points of the city are available from there. In the case of UU additional personal, private and public links appear. The Book to the Watcher's Pub (Sanctuary). This closed part of the city is the starting point of a separate mission in TPOTS. The Book of Er'cana leads to an Age with a big industrial complex in a canyon (TPOTS only) The Books of Ahnonay. Both Books link to the Age created by Master Kadish. One directly, the other via the so called Temple or Cathedral Age. (TPOTS only) The Book of Myst (perhaps already known?) (TPOTS only)