My impression was thus
The Descriptive Book forms the first link to the Age, and has to have such detail as to pick the "right" Age. The Descriptive Book gets a linking panel (see opening of Riven, Atrus is working on Riven's Descriptive Book), but I don't know how its link-in position is specified. So Descriptive Books point at the Age.
Linking Books form more links to the Age, and are bound to the point in space (relative to the planet anyway, otherwise D'ni links should put us in like Andromeda by now) that they are written. They point at the Descriptive Book ("I am a Linking Book for this Descriptive Book's Age"), and are fairly disposable, as seen with Atrus flinging the Myst Linking Book into the star fissure to kick off
Myst, then doing it again at the end of
Riven for the Stranger, and for sealing off the two prison Ages for
Revelation.
If you destroy the Linking Book, but the Descriptive Book is still intact, the Age is still accessible; just link in and write new Linking Books. You destroy the Descriptive Book, however, and that Age is gone from you (and all Linking Books stop working, I think); chaos pretty much guarantees that even if you write the exact same words in a new Descriptive Book, it'll still point at a different Age, albeit one "exactly" like the lost one.
This was all written down at some point on the original official Myst/Riven sites I think.
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