This document is a registry of supplementary members for the
Web Application Manifest specification that provide additional metadata to an
application manifest. This metadata can be used in a digital
storefront or other surfaces where this web application may be marketed
or distributed, or to enhance an installation dialog when installing a web application.
Status of This Document
This section describes the status of this
document at the time of its publication. A list of current W3C
publications and the latest revision of this technical report can be found
in the W3C technical reports index at
https://www.w3.org/TR/.
This is document is constantly evolving and we publish new snapshots
every time we commit a change. Interested parties can subscribe to
changes or even propose new manifest members in the manifest-app-info GitHub
repository.
This is a draft document and may be updated, replaced or obsoleted by other
documents at any time. It is inappropriate to cite this document as other
than work in progress.
The
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As web applications become available via more services (e.g., digital
storefronts, search results) where they are presented alongside native
applications, it becomes quite important for them to appear similarly
to their native counterparts. A web application can define both its
name and icons in the manifest, but those
keys do not provide enough information to help users determine whether
they might want to install it. Users have become accustomed to being
offered more details about the applications they consider installing,
and this document defines additional manifest members that can provide
that.
2.
Supplementary manifest members
The following members supplement the members of an application manifest. These members are classified as supplementary because they
are not applied to a web application at runtime (i.e., they are
purely advisory and don't affect how a user agent presents an
installed web application). All members are all optional and can
be added at the root of an application manifest, as shown in the
following example.
The categories member is an array of
strings that describes the application categories to which the
web application belongs. It is meant as a hint to catalogs or stores
listing web applications and it is expected that these will make a
best effort to find appropriate categories (or category) under which
to list the web application. Like search engines and meta keywords,
catalogs and stores are not required to honor this hint.
Manifest authors are encouraged to use lower-case.
The iarc_rating_id member is a string
that represents the International Age Rating Coalition
(IARC) certification code of the web application. It is intended
to be used to determine which ages the web application is appropriate
for.
Note
An IARC certificate can be obtained via participating storefronts,
intended to be used for distributing the web app. The
iarc_rating_id member only takes a single certification code.
The same code can be shared across participating storefronts, as long
as the distributed product remains the same (i.e., doesn’t serve
totally different code paths depending on user agent sniffing and the
like) and the other storefronts support it.
The screenshots member is an array of
screenshots objects, representing the web application in
common usage scenarios.
3.
Screenshot object and its members
A screenshots object is a ImageResourceobject
with some additional members as defined below.
3.1
label member
The label member is a string that
serves as the accessible name of that
screenshots object. For accessibility, authors are encouraged
to provide a label for each screenshot. This member can serve
as alternative text for the rendered screenshot.
{
"screenshots": [{
"src": "images/screenshot.png",
"sizes": "800x600",
"form_factor": "wide",
"label": "With Software, you can select a part of your screen and take a screenshot in seconds."
}]
}
3.2
platform member
The platform member is a string that
represents the distribution platform for which a given screenshot
applies. Authors are encouraged to only use this member when the
screenshot is only applicable in a specific context.
Note: Platform usage guidance for authors
Authors should only use platform for instances where a screenshot is
not representative of a universal experience. For instance, an
OS-specific platform designation should be reserved for instances
where the screenshot includes functionality only available on that
specific platform.
User agents might show as many (or as few) screenshots as they
choose, but shouldn't display screenshots that do not pertain to
their platform (e.g., Google Play should not show iOS-specific
screenshots).
When no platform is set, user agents should assume the screenshot
is applicable to all platforms.
User agents can use a screenshot’s aspect ratio
(sizes) in determining if the screenshot should be
displayed.
List of platform values that are specific to an operating system:
The form_factor member is a
string that represents the screen shape of a broad class of
devices for which a given screenshot applies. Authors are encouraged to
only use this member when the screenshot is only applicable in a
specific context.
Note: form_factor usage guidance for authors
Authors should only use form_factor for instances where a screenshot
is not representative of a universal experience. For instance, if the
layout/design differs based on the screen orientation, setting "narrow" or
"wide" is advisable.
User agents might show as many (or as few) screenshots as they choose,
but shouldn't display screenshots that do not pertain to their
form factor (e.g., mobile phones shouldn't show "wide" form_factor
screenshots).
When no form_factor is set, user agents should assume the
screenshot is applicable to all form factors.
List of form_factor values:
narrow
For screenshots applicable to narrow screens only (e.g., mobile devices).
wide
For screenshots applicable to wide screens only (e.g., status
boards).