[media-types] [IANA #1453672] application/vnd.portable web+zip registration request

Hi Murray,

Could you review this one by June 19th?

thanks,
Amanda

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Name: Omprakash Selvaraj

Email: [email protected]

Media type name: application

Media subtype name: vnd.portableweb+zip

Required parameters: N/A

Optional parameters: N/A

Encoding considerations: binary

Security considerations: PortableWeb files may contain active web content, including HTML, CSS, ECMAScript/JavaScript, WebAssembly if permitted by the viewer, and other resources referenced by the PortableWeb manifest. Implementations MUST treat PortableWeb files as untrusted content unless obtained from a trusted source.

PortableWeb content is intended to be processed by a PortableWeb viewer, not executed as native operating-system code. Viewers that render active content SHOULD do so in a sandboxed execution environment with no ambient access to the host application, local files, device APIs, credentials, cookies, or other user data except where the user explicitly grants access. Viewer implementations SHOULD isolate storage per PortableWeb package, restrict or mediate network access according to user or application policy, prevent script access to the viewer application's privileged user interface, and apply the security model of the underlying web rendering engine. Viewers SHOULD also prevent active content from escaping the sandbox through navigation, popups, downloads, same-origin confusion, or unrestricted access to host-provided APIs.

A PortableWeb package may include a manifest that declares the package's requested or expected capabilities, such as whether the package is intended to run offline, whether external network access is requested, which origins or URL patterns may be accessed, whether persistent storage is requested, and whether other higher-risk capabilities such as downloads, popups, external navigation, clipboard access, device APIs, or WebAssembly are requested. These manifest declarations are not security guarantees by themselves. They are inputs to the viewer's security policy. A viewer SHOULD apply a deny-by-default policy, SHOULD allow only the capabilities explicitly permitted by both the manifest and the viewer/user policy, and SHOULD keep storage, cache, cookies, and other persistent state isolated per PortableWeb package. A viewer MAY ignore or further restrict manifest-requested capabilities.

The media type itself does not provide confidentiality, integrity, authentication, authorization, or replay protection. PortableWeb files may contain private or sensitive information, and they may also contain active content whose behavior depends on the integrity of the package. Where confidentiality or integrity is required, it should be provided externally, such as by HTTPS/TLS during transport, a trusted distribution channel, operating-system file protections, digital signatures, checksums, or application-level validation. A viewer SHOULD make trust decisions based on the source and integrity of the package before enabling higher-risk capabilities.

PortableWeb files are ZIP-based binary containers. The security considerations for ZIP containers and compressed content apply. Implementations SHOULD protect against decompression bombs, excessive memory or disk usage, deeply nested archives, duplicate or ambiguous filenames, absolute paths, path traversal such as "../", symbolic links or platform-specific path handling issues, filename normalization conflicts, and mismatches between ZIP metadata and actual content. Implementations SHOULD impose reasonable limits on total uncompressed size, file count, nesting depth, path length, and individual resource size before extraction or rendering. Implementations SHOULD not extract files outside an application-controlled temporary or storage area.

PortableWeb packages may include resources using existing formats, including but not limited to JSON manifests, HTML, CSS, JavaScript, images, audio, video, fonts, and WebAssembly where supported. The security considerations for those formats also apply. Implementations SHOULD parse the manifest strictly, avoid unsafe content sniffing, validate resource references against the manifest and package boundaries, and avoid granting additional privileges based only on file extension or declared media type.

PortableWeb packages may contain internal links between packaged resources and may optionally contain external links. External network resources are not required to interpret a conforming local PortableWeb package unless explicitly allowed by the package profile and viewer policy. Viewers SHOULD clearly distinguish packaged local resources from external resources and SHOULD mediate or block external navigation and network requests according to user or application policy.

Interoperability considerations: PortableWeb packages are ZIP-based containers with a manifest that identifies the package structure, entry resource, declared capabilities, and packaged resources. Interoperability depends on viewers interpreting the manifest consistently, resolving resource paths consistently, and enforcing package boundaries consistently.

Implementations SHOULD use UTF-8 for manifest data and resource identifiers, SHOULD treat resource paths as case-sensitive package-relative paths, and SHOULD avoid relying on platform-specific filesystem behavior such as case-insensitive matching, absolute paths, drive letters, symbolic links, or path separators other than "/". Viewers SHOULD reject or normalize ambiguous paths, duplicate entries, and references that resolve outside the package.

PortableWeb packages may contain common web resource formats such as HTML, CSS, JavaScript, JSON, images, fonts, audio, video, and other media. Rendering behavior may vary between web engines, operating systems, and viewer implementations, especially for optional web platform features, media codecs, fonts, storage behavior, network policy, and device APIs. Package authors SHOULD use widely supported web standards and SHOULD declare required or requested capabilities in the manifest. Viewers SHOULD ignore unknown manifest fields that are not required for safe processing, and packages SHOULD be designed to fail gracefully when optional capabilities are unavailable.

A conforming local PortableWeb package should be interpretable using only the resources contained in the package, unless the manifest and viewer policy explicitly allow external network access. Implementations SHOULD clearly distinguish packaged resources from external resources and SHOULD apply consistent origin, storage, and caching rules for each package.

The ".pweb" file extension and the "application/vnd.portableweb+zip" media type identify the package as a PortableWeb package. Operating systems, browsers, and applications may vary in how they associate file extensions, media types, icons, and document-opening behavior. Applications that support this media type SHOULD inspect and validate the package manifest and container structure rather than relying only on the filename extension or declared media type.

Published specification: https://github.com/portableweb/spec/blob/main/spec/MANIFEST.md
https://github.com/portableweb/spec/blob/main/spec/CONTAINER.md
https://portableweb.org

Applications which use this media: This media type is intended for use by applications that create, distribute, inspect, validate, store, or render PortableWeb .pweb packages.

Typical applications include PortableWeb viewer applications, authoring tools, packaging tools, validation tools, document-management systems, file managers, web servers, content-distribution systems, and collaboration or archival systems that need to identify PortableWeb packages by media type or file extension.

A PortableWeb viewer may open a .pweb package as a self-contained interactive document, presentation, game, educational module, demonstration, or other packaged web-based experience. Developer and authoring tools may use this media type when creating, exporting, importing, testing, or validating PortableWeb packages.

Operating systems and application platforms may also use this media type and the .pweb file extension for file association, document opening, icons, previews, sharing, and handoff to applications that support PortableWeb packages.

This format is useful for interactive presentations, educational explainers, games, scientific journals and supplements, interactive reports, reproducible simulations, personal tools, calculators, planners, journals, and other packaged web-based experiences.

PortableWeb is also intended to support AI-generated interactive artifacts. AI tools are increasingly capable of producing large numbers of small, useful web applications and interactive documents. Not all such artifacts need to be deployed to a web server in order to be useful. A .pweb package gives users, authors, and AI tools a way to package such content as a file, preserve it, send it, and view it elegantly in a compatible viewer application.

Fragment identifier considerations: Fragment identifier semantics are not defined by this media type registration for the PortableWeb package container as a whole.

A PortableWeb package is a ZIP-based container that may include resources such as HTML, CSS, JavaScript, JSON, images, media, and other files. Fragment identifiers, where used inside packaged resources, are interpreted according to the rules of the individual resource media type, such as HTML fragment navigation within an HTML document.

A PortableWeb viewer MAY support application-specific navigation behavior for fragment identifiers, such as forwarding a fragment to the package's declared entry resource, but such behavior is viewer-defined unless specified by the PortableWeb specification. Fragment identifiers MUST NOT be treated as granting access to resources or capabilities that are not otherwise allowed by the package manifest and viewer security policy.

If a future version of the PortableWeb specification defines PortableWeb-specific fragment identifier syntax for addressing packaged resources or internal navigation targets, this registration should be updated to describe those semantics.

Restrictions on usage: There are no restrictions on usage imposed by this media type registration.

PortableWeb .pweb packages may be created, distributed, stored, opened, inspected, validated, and rendered by any application or platform that supports the PortableWeb format. Use of this media type is not limited to a particular operating system, application store, browser engine, vendor, or viewer implementation.

Applications that process PortableWeb packages are expected to follow the PortableWeb specification and apply appropriate security controls for active content, storage, networking, and package validation.

Provisional registration? (standards tree only): No

Additional information:

1. Deprecated alias names for this type: N/A
2. Magic number(s): 50 4B 03 04 (PK\003\004) (.pweb files are ZIP-based containers and therefore use the ZIP container signatures)
3. File extension(s): .pweb
4. Macintosh file type code: N/A
5. Object Identifiers: N/A

General Comments: PortableWeb .pweb packages are intended to provide a portable, self-contained packaging format for interactive web-based content that can be saved, shared, archived, and opened like a document while still behaving like an application inside a controlled viewer.

This format is useful for interactive presentations, educational explainers, games, scientific journals and supplements, interactive reports, reproducible simulations, personal tools, calculators, planners, journals, and other packaged web-based experiences.

PortableWeb is also intended to support AI-generated interactive artifacts. AI tools are increasingly capable of producing large numbers of small, useful web applications and interactive documents. Not all such artifacts need to be deployed to a web server in order to be useful. A .pweb package gives users, authors, and AI tools a way to package such content as a file, preserve it, send it, and view it elegantly in a compatible viewer application.

The format is designed to be opened by viewer applications that validate the package, read the PortableWeb manifest, and render the packaged resources under an application-defined security policy. The .pweb file extension is the preferred extension for this media type.

Specification and project information are available at:

https://portableweb.org

https://github.com/portableweb/spec

Person to contact for further information:

1. Name: Omprakash Selvaraj
2. Email: [email protected]

Intended usage: COMMON

Author/Change controller: PortableWeb Project

Contact: Omprakash Selvaraj [email protected]

Change control for this registration is maintained by the PortableWeb Project and its specification maintainers.

Specification repository:

https://github.com/portableweb/spec

Project website:

https://portableweb.github.io
https://portableweb.org

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