Physical Package

In contrast to the package model that describes the contents of a package in an abstract way, the physical package refers to a package that is stored in a particular physical file format. This includes the physical model and physical mapping considerations.

The physical model abstractly describes the capabilities of a particular physical format and how producers and consumers can use a package implementer to interact with that physical package format. The physical model includes the access style, or the manner in which package input-output is conducted, as well as the communication style, which describes the method of interaction between producers and consumers across a communications pipe. The physical model also includes the layout style, or how part contents are physically stored within the package. The layout style can either be simple ordering, where the parts are arranged contiguously as atomic blocks of data, or interleaved ordering, where the parts are broken into individual pieces and the pieces are stored as interleaved blocks of data in an optimized fashion. The performance of a physical package design is reliant upon the physical model capabilities.


Physical mappings describe the manner in which the package contents are mapped to the features of that specific physical format. Details of how package components are mapped are described, as well as common mapping patterns and mechanisms for storing part content types. This Open Packaging specification describes both the specific considerations for physical mapping to a ZIP archive as well as generic physical mapping considerations applicable to any physical package format.