1.3.1 is a major update to Java Edition released on August 1, 2012, which added trading, Adventure mode, new generated structures (jungle and desert pyramids), and new blocks/items including emeralds, book and quills, written books, and tripwire. It also adds ender chests, improved enchanting, and splits the Creative inventory into separate sections. This is the first version to use an internal multiplayer server in singleplayer worlds, which resulted in many broken features. While it was not the only 1.3 release, it was the only one before the snapshots of 1.4.2 started.
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