For the purposes of this Open Packaging specification, the following definitions apply. Other terms are defined where they appear in italic type. Terms explicitly defined in this Open Packaging specification are not to be presumed to refer implicitly to similar terms defined elsewhere.

The terms base URI and relative reference are used in accordance with RFC 3986.

access style — The style in which local access or networked access is conducted. The access styles are as follows: streaming creation, streaming consumption, simultaneous creation and consumption, and direct access consumption.

behavior — External appearance or action.

behavior, implementation-defined — Unspecified behavior where each implementation shall document that behavior, thereby promoting predictability and reproducibility within any given implementation. (This term is sometimes called “application-specific behavior”.)

behavior, unspecified —Behavior where this Open Packaging specification imposes no requirements.

communication style — The style in which package contents are delivered by a producer or received by a consumer. Communication styles include: random access and sequential delivery.

consumer — A piece of software or a device that reads packages through a package implementer. A consumer is often designed to consume packages only for a specific physical package format.

content type — Describes the content stored in a part. Content types define a media type, a subtype, and an optional set of parameters, as defined in RFC 2616.

Content Types stream — A specially-named stream that defines mappings from part names to content types. The content types stream is not itself a part, and is not URI addressable.

device — A piece of hardware, such as a personal computer, printer, or scanner, that performs a single function or set of functions.

format consumer — A consumer that consumes packages conforming to a format designer's specification.

format designer — The author of a particular file format specification built on this Open Packaging Conventions specification.

format producer — A producer that produces packages conforming to a format designer's specification.

growth hint — A suggested number of bytes to reserve for a part to grow in-place.

interleaved ordering — The layout style of a physical package where parts are broken into pieces and “mixed-in” with pieces from other parts. When delivered, interleaved packages can help improve the performance of the consumer processing the package.

layout style — The style in which the collection of parts in a physical package is laid out: either simple ordering or interleaved ordering.

local access — The access architecture in which a pipe carries data directly from a producer to a consumer on a single device.

logical item name — An abstraction that allows package implementers to manipulate physical data items consistently regardless of whether those data items can be mapped to parts or not or whether the package is laid out with simple ordering or interleaved ordering.

networked access — The access architecture in which a consumer and the producer communicate over a protocol, such as across a process boundary, or between a server and a desktop computer.

pack URI — A URI scheme that allows URIs to be used as a uniform mechanism for addressing parts within a package. Pack URIs are used as Base URIs for resolving relative references among parts in a package.

package — A logical entity that holds a collection of parts.

package implementer — Software that implements the physical input-output operations to a package according to the requirements and recommendations of this Open Packaging specification. A package implementer is used by a producer or consumer to interact with a physical package. A package implementer may be either a stand-alone API or may be an integrated component of a producer, consumer application, or device.

package model — A package abstraction that holds a collection of parts.

package relationship — A relationship whose target is a part and whose source is the package as a whole. Package relationships are found in the package relationships part named “/_rels/.rels”.

part — A stream of bytes with a MIME content type and associated common properties. Typically corresponds to a file
example: : on a file system
, a stream
example: : in a compound file ], or a resource [
example: : in an HTTP URI

part name — The path component of a pack URI. Part names are used to refer to a part in the context of a package, typically as part of a URI.

physical model — A description of the capabilities of a particular physical format.

physical package format — A specific file format, or other persistence or transport mechanism, that can represent all of the capabilities of a package.

piece — A portion of a part. Pieces of different parts may be interleaved together. The individual pieces are named using a unique mapping from the part name. Piece name grammar is not equivalent to the part name grammar. Pieces are not addressable in the package model.

pipe — A communication mechanism that carries data from the producer to the consumer.

producer — A piece of software or a device that writes packages through a package implementer. A producer is often designed to produce packages according to a particular physical package format specification.

random access — A style of communication between the producer and the consumer of the package. Random access allows the consumer to reference and obtain data from anywhere within a package.

relationship —The kind of connection between a source part and a target part in a package. Relationships make the connections between parts directly discoverable without looking at the content in the parts, and without altering the parts themselves. (See also Package Relationships.)

relationships part — A part containing an XML representation of relationships.

sequential delivery — A communication style in which all of the physical bits in the package are delivered in the order they appear in the package.

signature policy — A format-defined policy that specifies what configuration of parts and relationships shall or might be included in a signature for that format and what additional behaviors that producers and consumers of that format shall follow when applying or verifying signatures following that format's signature policy.

simple ordering — A defined ordering for laying out the parts in a package in which all the bits comprising each part are stored contiguously.

simultaneous creation and consumption — A style of access between a producer and a consumer in highly pipelined environments where streaming creation and streaming consumption occur simultaneously.

stream — A linearly ordered sequence of bytes.

streaming consumption — An access style in which parts of a physical package may be processed by a consumer before all of the bits of the package have been delivered through the pipe.

streaming creation — A production style in which a producer dynamically adds parts to a package after other parts have been added without modifying those parts.

thumbnail — A small image that is a graphical representation of a part or the package as a whole.

well-known part — A part with a well-known relationship, which enables the part to be found without knowing the location of other parts.

ZIP archive — A ZIP file as defined in the ZIP file format specification. A ZIP archive contains ZIP items.

ZIP item — A ZIP item is an atomic set of data in a ZIP archive that becomes a file when the archive is uncompressed. When a user unzips a ZIP based package, the user sees an organized set of files and folders.