Quetzal
From IFWiki
Quetzal stands for Quetzal Unifies Efficiently The Z-Machine Archive Language. Quetzal is also called the Z-machine Common Save-File Format Standard. It specifies the way how Z-machine interpreters should create a save-file.
The Quetzal standard was created by Martin Frost. Quetzal Version 1.4 is available at the IF Archive.