The Open Packaging Conventions is specified in ISO/IEC 29500-2:2021 and ECMA-376. It is a container-file technology. The Open Packaging Conventions use a Package model that holds a collection of Parts. ZIP archives that contain XML, binary, and other types of files make up an Open Package Conventions-based document. The independent files (or Parts) remain intact in the document and are compressed into a single file container. This provides the advantages of file independence, smaller file size, and a single integrated document for storage.

An Open Package Conventions Package, shown in Figure G., is an aggregate of Parts and References. A Part is the application data files, such as binary files or text files. Relationships are references between Parts in the Package and resources outside the Package.


Figure G.1 – Sample relationship and associated markup