The document describes mm-ADT, a proposed multi-model abstract datatype that aims to provide a universal data structure, processing model, and instruction set that can support various database models like graph, document, relational etc. in a common framework. Key goals are to release a stable mm-ADT specification, compiler and virtual machine, as well as a basic reference implementation by early 2020. The presentation focuses on the universal data structure component, describing how mm-ADT would define custom datatypes, instances, access paths and more using a bytecode language.