Enchantment names are randomly constructed from the following list of words. Three to five words are chosen from the list and appended to each other, then displayed in the Standard Galactic Alphabet. Note that the names have no meaning and are not saved on the enchanted item (meaning they will tell you nothing about what the resulting spell will be), and they are only displayed in the Enchantment Table interface.
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This might help to decide which one is the best for you.
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Also you should look at the source, since your level is modified by the tool/material of the tool. And what you get is randomized of the possible enchantment. A few of these enchantment have more "weight" during this randomization, you can find a table for the enchantment weight also on the linked page.
What is an enchanted book?
According to the Minecraft Wiki, an enchanted book is an item which allows players to add enchantments to weapons, tools, or armor by combining the enchantment book with one of said items on an anvil.
Can they receive any enchantment?
Testing in creative and survival mode shows that books can receive any enchantment that a normal weapon/armor/tool/other can receive. An easy way to check is to go into creative mode and use the new search function to search for the term book. This will show you what all the enchanted books are.
Can they receive more than one enchantment?
According to the wiki, books may only have one enchantment. This can be tested by giving yourself a bunch of books and enchanting them, then throwing them into lava or whatever you wish to do with them.
Since enchantments have different chances of occurring for different tools, materials, and at different levels, how are those probabilities different for books?
This would be different for books since books are not diamond swords. However, this would have that many variables because unlike a sword, books can only be made from paper. Swords can be made from diamonds, iron, and other materials. You would have to test this to truly know, but if John tells us how many levels he invested into his enchanted books, we might be able to know. Right now, though, it appears that the enchantment gives you the highest level (ex. Protection IV, Sharpness IV, etc.)
Best Answer
Correct me if I'm wrong, but the only way would be to add command blocks for every single armor enchant and level combo in the game. (Unless you wanted to host a server on your computer running bukkit and just not allow anyone in. Then you could download essentials and use /enchant )