Quetzal file format
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Quetzal is a standardised file format for the saved state of Z-machine games, invented by Martin Frost. Prior to the introduction of Quetzal, each Z-machine interpreter saved games in its own format; Quetzal enabled players to begin a game on one architecture (for example, a pocket computer) and end it on another. Use of the format is strongly recommended in Graham Nelson's Z-machine standards document, but not obligatory. All modern Z-machines have the ability to save Quetzal files.
The files are IFF files with a FORM of "IFZS" (presumably standing for "interactive fiction Z-machine save"), although the saved files are commonly given an extension of "sav": less commonly sighted are "quz" and "qtz". Despite the reference to the Z-machine in the FORM code, the format has proved flexible enough to be adapted for at least one alternative architecture, Glulx.
The format's name is a backronym for "Quetzal Unifies Efficiently The Z-Machine Archive Language".
Version 1.3b, which is widely available, contains a bug later corrected in version 1.4: after a save instruction, the Z-machine requires that a success code is saved in a particular place (which differs depending on the version). Versions of the Quetzal standard before 1.4 have reference only to the instruction after the save, which complicates finding the correct place to put the success code.
