Abstract

This document describes a JSON serialization format to describe simple streams of data as well as single objects of data for data transfer and processing.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. 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 document was published by the Social Web Working Group as a Working Draft. Comments regarding this document are welcome. Please send them to public-socialweb@w3.org (subscribe, archives).

Publication as a Working Draft does not imply endorsement by the W3C Membership. 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.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. The group does not expect this document to become a W3C Recommendation. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 March 2017 W3C Process Document.

1. Author's Note

This section is non-normative.

This document is an attempt to unify various simplified versions of the Microformats-2 representative JSON format. As such, much of this document is likely to change as various implementations contribute input.

2. Introduction

This section is non-normative.

JF2 is a JSON based document format that describes lists and single entries of information. The primary use case for JF2 is to create a JSON format for social web post objects to be processed directly by client software and by other servers.

The name JF2 comes from its origins in being a direct parsed format of Microformats-2 (MF2) data from html. Rather than defining a new vocabulary, JF2 uses the vocabulary defined by [microformats2] however any other suitable vocabulary could be used. JF2 is vocabulary independent except for its profiles which are fully vocabulary aware.

3. Use Cases

This section is non-normative.

JF2 has evolved as a result of a variety of use-cases for different implementations exploring ways to simplify their existing use of canonical parsed microformats2 JSON output. All of these use cases in particular are simply to have a single format for the storage and use of social web objects.

Webmention.io is a service that provides webmention processing and verification on behalf of other sites. It uses a simple JSON object to transfer a processed webmention back to the client site's javascript for display. The attributes are intended to be processed only by the client site's javascript code, not by anything else.

mf2util is a utility library that provides a layer on top of microformats processing. The library returns only a simple JSON object and strips off any unnecessary information leaving the library user only the most essential information.

Various services (xray, unmung, socialstreams) provide conversion from microformats pages in to JF2 for quick inspection to validate proper semantics.

4. Syntax

JF2 consists of JSON objects which are defined by a type property that will specify the vocabulary of the object. Properties are attached to these objects which will contain either a single string, a single object, an array of strings, or an array of objects. Arrays that have only a single item SHOULD be condensed into only the single containing item. Any property of an object MAY be a single item or an array of items except for reserved words defined below.

4.1 Reserved Keywords

The following keywords are reserved and cannot be used as property names in vocabularies.

4.2 Posts

4.2.1 Post Objects

A post is composed of a "type" property, and one or more additional properties that describe the post.

The "type" property has a value that describes the vocabulary of this post. Common values include "entry", "card", etc. See Microformats 2 vocabularies for the full list when using a microformats based vocabulary.

Any additional properties in the post object are considered part of the post's vocabulary.

4.2.2 Post Properties

The list of valid post properties is defined by the vocabularies. This allows new vocabularies to be developed outside the development of the syntax.

Most values will be strings. If a property (such as `author` for example) references another object, it may be serialized in two ways: as an object serialized as the property value or as the unique identifier or URL where the object can be found. See Using References

Values may also be arrays if the vocabulary allows for multiple values of the property.

4.2.3 Example Post

Example 1
{
  "type": "entry",
  "published": "2015-10-20T15:49:00-0700",
  "url": "http://example.com/post/fsjeuu8372",
  "author": {
    "type": "card",
    "name": "Alice",
    "url": "http://alice.example.com",
    "photo": "http://alice.example.com/photo.jpg"
  },
  "name": "Hello World",
  "content": "This is a blog post",
  "category": "Posts"
}
Example 2
{
  "type": "entry",
  "published": "2015-10-20T15:49:00-0700",
  "url": "http://example.com/like/r23eugi02c",
  "author": {
    "type": "card",
    "name": "Alice",
    "url": "http://alice.example.com",
    "photo": "http://alice.example.com/photo.jpg"
  },
  "like-of": "http://bob.example.com/post/100",
  "category": ["Likes", "Posts"]
}

4.3 Author

An author is represented by the h-card vocabulary, and consists of a name, photo URL, URL to the author profile, and [others](http://microformats.org/wiki/h-card). This is represented by the following JSON.

Example 3
{
  "type": "card",
  "name": "Aaron Parecki",
  "photo": "http://aaronparecki.com/photo.jpg",
  "url": "http://aaronparecki.com/"
}

4.4 HTML Content

By default, any string value should be interpreted as literal plaintext. This means when displaying a string in an HTML page, it must be HTML escaped.

If the value of a property is to be interpreted as HTML, it MUST be enclosed in an object and placed under the "html" property as follows. If a plaintext version is also available, that is placed under the "text" property.

Example 4
{
  "type": "entry",
  "content": {
    "html": "<p>Hello World</p>"
    "text": "Hello World"
  }
}

4.4.1 Multiple URLs for video/audio/picture

Since HTML video/audio/picture tags may have multiple URLs, we need a way to convey this information in the JSON representation.

Example 5
<div class="h-entry">
  <video class="u-video" width="640" height="360" preload controls>
    <source src="sample_h264.mov" type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"' />
    <source src="sample_ogg.ogv" type='video/ogg; codecs="theora, vorbis"' />
    <source src="sample_webm.webm" type='video/webm; codecs="vp8, vorbis"' />
  </video>
</div>
Example 6
{
  "type": "entry",
  "video": [
    {
      "content-type": "video/mp4",
      "url": "sample_h264.mov"
    },
    {
      "content-type": "video/ogg",
      "url": "sample_ogg.ogg"
    },
    {
      "content-type": "video/webm",
      "url": "sample_webm.webm"
    }
  ]
}

5. Using References

The purpose of the `references` property is to exclude any non-authoritative data from the defined object. To do this, non-authoritative data is moved so that implementations looking to process only authoritative data may simply ignore the references property and fetch any data that would be contained there from its authoritative source.

If a property is a reference to an object that is defined authoritatively in some other location, the `references` property SHOULD be used. The property SHOULD contain only the unique identifier or URL where the authoritative data may be found. In the references object, the URL or unique identifier MAY be entered as the key field and a serialization of the referenced object MAY be provided. This serialization of the referenced object MAY be incomplete so as to provide only necessary data.

Parsing implementations SHOULD fetch data from the authoritative source instead of using the references object.

5.1 Example of References

Example 7
{
  "type": "entry",
  "published": "2015-10-20T15:49:00-0700",
  "url": "http://example.com/post/fsjeuu8372",
  "author": "http://alice.example.com",
  "name": "Hello World",
  "content": "This is a blog post",
  "category": "Posts",
  "references": {
    "http://alice.example.com": {
      "type": "card",
      "name": "Alice",
      "url": "http://alice.example.com",
      "photo": "http://alice.example.com/photo.jpg"
    }
  }
}
Example 8
{
  "type": "entry",
  "published": "2015-10-20T15:49:00-0700",
  "url": "http://example.com/like/r23eugi02c",
  "author": {
    "type": "card",
    "name": "Alice",
    "url": "http://alice.example.com",
    "photo": "http://alice.example.com/photo.jpg"
  },
  "like-of": "http://bob.example.com/post/100",
  "category": ["Likes", "Posts"],
  "references": {
    "http://bob.example.com/post/100": {
      "type": "entry",
      "published": "2015-10-18T12:33:00-0700",
      "url": "http://bob.example.com/post/100",
      "author": "http://bob.example.com",
      "name": "My First Post",
      "content": "This is my first post on my new blog, I hope you like it"
    },
    "http://bob.example.com": {
      "type": "card",
      "name": "Bob",
      "url": "http://bob.example.com",
      "photo": "http://bob.example.com/mypicture.jpg"
    }
  }
}

6. Collections

Posts can live inside of collections. A collection may be a home page feed, or a feed of other posts such as a list of contacts, a list of things someone has liked, etc. There is no requirement that all posts in a collection need to be of the same type.

The collection may also have its own properties such as "name" or "author".

Example 9
{
  "type": "feed",
  "url": "http://alice.example.com/collectionurl",
  "name": "Alice's Home Page",
  "author": {
    "type": "card",
    "name": "Alice",
    "url": "http://alice.example.com",
    "photo": "http://alice.example.com/photo"
  },
  "children": [
    { ... },
    { ... }
  ]
}

6.1 Multiple items on a page

If an HTML page contains multiple top-level items, (most commonly found when a page contains a list of [h-entry] objects), the parser creates an implicit top-level collection with no properties.

Example 10
{
  "children": [
    { ... },
    { ... }
  ]
}

7. Deriving the Syntax

This syntax is derived from HTML with Microformats-2, converted to JSON [microformats2-parsing] converted to a simplified JSON. The examples below illustrate the process.

7.1 Deriving a Note

HTML + Microformats

Example 11
<article class="h-entry">
  <h1 class="p-name">Hello World</h1>
  <p>Published by <a class="p-author h-card" href="http://example.com/">A. Developer</a>
     on <a href="http://example.com/2015/10/21" class="u-url"><time class="dt-published" datetime="2015-10-21T12:00:00-0700">October 21<sup>st</sup>, 2015</time></a>
 
  <p class="p-summary">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus imperdiet ultrices pulvinar.</p>
 
  <div class="e-content"><p>Donec dapibus enim lacus, <i>a vehicula magna bibendum non</i>. Phasellus id lacinia felis, vitae pellentesque enim. Sed at quam dui. Suspendisse accumsan, est id pulvinar consequat, urna ex tincidunt enim, nec sodales lectus nulla et augue. Cras venenatis vehicula molestie. Donec sagittis elit orci, sit amet egestas ex pharetra in.</p></div>
</article>

Parsed Microformats JSON

Example 12
{
  "items": [
    {
      "type": [
        "h-entry"
      ],
      "properties": {
        "author": [
          {
            "type": [
              "h-card"
            ],
            "properties": {
              "name": [
                "A. Developer"
              ],
              "url": [
                "http:\/\/example.com\/"
              ]
            },
            "value": "A. Developer"
          }
        ],
        "name": [
          "Hello World"
        ],
        "summary": [
          "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus imperdiet ultrices pulvinar."
        ],
        "url": [
          "http:\/\/example.com\/2015\/10\/21"
        ],
        "published": [
          "2015-10-21T12:00:00-0700"
        ],
        "content": [
          {
            "html": "<p>Donec dapibus enim lacus, <i>a vehicula magna bibendum non</i>. Phasellus id lacinia felis, vitae pellentesque enim. Sed at quam dui. Suspendisse accumsan, est id pulvinar consequat, urna ex tincidunt enim, nec sodales lectus nulla et augue. Cras venenatis vehicula molestie. Donec sagittis elit orci, sit amet egestas ex pharetra in.</p>",
            "value": "Donec dapibus enim lacus, a vehicula magna bibendum non. Phasellus id lacinia felis, vitae pellentesque enim. Sed at quam dui. Suspendisse accumsan, est id pulvinar consequat, urna ex tincidunt enim, nec sodales lectus nulla et augue. Cras venenatis vehicula molestie. Donec sagittis elit orci, sit amet egestas ex pharetra in."
          }
        ]
      }
    }
  ]
}

Simplified JSON

Example 13
{
  "type": "entry",
  "author": {
    "type": "card",
    "url": "http://example.com",
    "name": "A. Developer"
  },
  "url": "http://example.com/2015/10/21",
  "published": "2015-10-21T12:00:00-0700",
  "name": "Hello World",
  "summary": "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus imperdiet ultrices pulvinar.",
  "content": {
    "value": "<p>Donec dapibus enim lacus, <i>a vehicula magna bibendum non</i>. Phasellus id lacinia felis, vitae pellentesque enim. Sed at quam dui. Suspendisse accumsan, est id pulvinar consequat, urna ex tincidunt enim, nec sodales lectus nulla et augue. Cras venenatis vehicula molestie. Donec sagittis elit orci, sit amet egestas ex pharetra in.</p>",
    "text": "Donec dapibus enim lacus, a vehicula magna bibendum non. Phasellus id lacinia felis, vitae pellentesque enim. Sed at quam dui. Suspendisse accumsan, est id pulvinar consequat, urna ex tincidunt enim, nec sodales lectus nulla et augue. Cras venenatis vehicula molestie. Donec sagittis elit orci, sit amet egestas ex pharetra in."
  }
}

7.2 JSON-LD Consideration

JF2 documents all have an implicit @context field which is optional. This @context can be found at http://www.w3.org/ns/jf2 and is provided only to make conversion to [JSON-LD] format possible. Most JF2 will process fine in JSON-LD systems, however, this support is not guaranteed and those wishing to use JF2 in JSON-LD may need to modify serialization slightly.

8. Profiles

8.1 Intro

This section is non-normative.

JF2 on its own is intentionally vocabulary independent, that is, any value may contain a single value, a set of values, or a structure and there are no requirements that fields be present. While this keeps the fidelity of the original [microformats2] encoded html, some consuming code can be simplified by adding vocabulary requirements. This creates the need for vocabulary aware profiles of JF2, where the profile adds additional constraints on the fields present.

8.2 JF2 Feed

8.2.1 Introduction

This section is non-normative.

XML formats have heavily dominated serializations of social activity feeds for blogs and news feeds for years. Several attempts have been created over the years to attempt to bring these to a JSON format, most recently [ jsonfeed-v1], which JF2 Feed gets the majority of its requirements from. JF2 Feed is an attempt to bring some of the advantages of these vocabulary aware specifications under a standard vocabulary from [ microformats2].

Fields described below have additional requirements to be considered a valid JF2 Feed, however they may contain any number of additional fields from [h-feed], [h-entry], and [h-card]. The entries below are codified as they are likely the most useful for feed readers and additional data is expected to be fetchable at the entry URL, preferrably though valid [microformats2] markup.

8.2.2 Required Fields and Required Formats

The following fields have additional constraints to be a valid JF2 Feed that only apply to the top level feed object, its child entry object, and any properties of them.

  • type MUST be defined with a value of "feed" on the top level entry. All other sub-object items MUST NOT have a type value of "feed". All direct children of the top level feed object MUST have a value of "entry".
  • name MUST be defined on the top level "feed" object. This value MUST be a single string value. Any direct children of the top level item SHOULD have this property and if present MUST be a single string value.
  • url SHOULD be defined on the top level "feed" object. This value MUST be a single string value and is expected to contain the URL of the data which this JF2 Feed describes. Additionally, if present in the author property object, or any direct child entry object, it MUST contain a single string value only and that value must be a [URL].
  • photo MUST be a single string value if present on the top level feed object, its author property object, or any direct child entry object and MUST be a valid [URL].
  • uid MUST be present on any entry object which is a direct child of the top level feed object. This property MUST be a single string value and MUST uniquely identify this entry object. This MAY be a duplicate of the entry's url property.
  • published SHOULD be present on any entry object which is a direct child of the top level feed object. If present, this property MUST be a single string value and MUST be formatted as specified by [ISO8601].
  • updated MAY be present on any entry object which is a direct child of the top level feed object. If present, this property MUST be a single string value and MUST be formatted as specified by [ISO8601].
  • category MAY be present on any entry object which is a direct child of the top level feed object. If present, this property MUST be an array of string values.
  • author MAY be present on the top level feed or second level entry objects. If present, it MUST be an object and it MUST contain at least a name, url, or photo property.
  • content MAY be present on any entry object which is a direct child of the top level feed object. If present, this property MUST be an object as described in the html content regardless if only a text/plain version is available.
  • summary MAY be present on any second level entry object. If present, it MUST be a single string.
  • video or audio MAY be present on any second level entry object. If present, it MUST be an object as described in multiple urls section with at least a 'url' property which MUST be a single string and a valid [URL].
Note

The format of published and updated fields may change from [ISO8601] to [RFC3339] or use [microformats2]'s more liberal date field. Please discuss on github issues

8.2.3 Discovery

The JF2 Feed for a page may be published as HTTP Link header [RFC5988], or as an HTML <link> or <a> tag element with the following attributes. 

rel="alternate" type="application/jf2feed+json" href="http://www.example.com/jf2feed.json"

8.2.4 JF2 Feed Example

Example 14
{
    "type": "feed",
    "url": "https://example.org/myfeed.html",
    "name": "Brent Simmons’s Microblog",
    "author": {
        "type": "card",
        "name": "Brent Simmons",
        "url": "http://example.org/",
        "photo": "https://example.org/avatar.png"
    },
    "children": [
        {
            "type": "entry",
            "uid": "https://example.org/2347259",
            "url": "https://example.org/2347259",
            "content": {
              "text": "Cats are neat. \n\nhttps://example.org/cats"
            },
            "published": "2016-02-09T14:22:00-07:00"
        }
    ]
}

8.2.5 JSON Feed to JF2 conversion

This section is non-normative.

Note

As it is not sane to do this for every feed serialization currently available, this section is likely to only be temporary in the spec and may be moved to a more permanant home elsewhere.

JF2 Feed was based heavily on [jsonfeed-v1] and as such it is quite trivial to process a JSON Feed as a JF2 Feed with only minor changes. This section discusses the conversion that must be made for this process, most of which is simply conversion of properties to their [ microformats2] equivalent.

Conversion of the top level sturcture

  • Drop or ignore the "version" property
  • Create a property "type" with the value "feed"
  • Rename the properties "title" to "name", "home_page_url" to "url", "icon" to "photo", and "description" to "summary"
  • Modify the "author" property as described below
  • Rename the "items" property to "children" and modify as described below

Conversion of the author property on the top level or on any lower level entry

  • Rename the property 'avatar' to 'photo'

Conversion each entry in items

  • Rename the 'id' property to 'uid'
  • Convert content_html and content_text in to a single object under the property "content" with properties "html" and "text", leaving out either if not present, or the entire property if neither are present.
  • Rename the properties "title" to "name", "image" to "photo", "date_published" to "published", "date_modified" to "updated", "tags" to "category", "banner_image" to "featured"
  • Drop or ignore the 'external_url' property. If content is not set, it may be useful to set content['text'] to the value of 'external_url'
  • Keep "summary" property the same
  • For each entry in the "attachments" array,
    1. Rename "mime-type" to "content-type".
    2. Keep the "url" property as is.
    3. If the "content-type" field begins with "video/", add the item to the "video" property array.
    4. If the "content-type" field begins with "photo/", add the item to the "photo" property array.

It may be benefitial to drop any properties other than those mentioned to avoid conflicts with any future [microformats2] properties.

9. Extension

JF2 MAY be extended by the [microformats2] extension mechanism. The 'x-*' properties created in this way MAY be present in any serialization of JF2. Parsers MUST NOT halt on any unknown properties they encounter.

10. Language And Internationalization

This section is non-normative.

In order to allow any language to be serialized in JF2, the 'lang' value can be set on any object to inform annotate the natural language of the text. Many often ask for control structures like directionality of text and multiple language serializations. Directionality of text can be accomplished with UTF-8 control characters which can be added to any of the values in the document. In addition, any content inside of 'html' properties can have any markup as defined by [HTML5].

Multiple serializations of the same text has not been seen to be needed in practice. The suggested path for accomplishing this with JF2 is to have these hosted at different locations. For example, it is common practice on websites to host an alternate language version of a site under a different directory structure for each language (such as /en/, /jp/, /fr/, etc).

11. Implementations

This section is non-normative.

The following is a list of currently known implementations of JF2-like formats and their current differences to this document

11.1 Webmention.io

Webmention.io is a hosted service for handling webmentions. Webmentions are accessed from an API that that returns a set of objects in JSON format similar to JF2. The key difference is the inclusion of some additional data wrapping the objects (source, verified, verified_data, etc) and all wrapped in a "links" array. Code available at https://github.com/aaronpk/webmention.io

11.2 XRay

X-Ray is a tool to return structured data from any URL. Code available at https://github.com/aaronpk/XRay

11.3 Unmung

Unmung is a tool for converting various formats. Code available at https://github.com/kevinmarks/unmung

11.4 SocialStreams

SocialStreams is a translation service for converting social formats. Code available at https://github.com/dissolve/socialstream

11.5 mf2util

Mf2util is a utility library for interpreting microformats2. Code available at https://github.com/kylewm/mf2util

12. Privacy Considerations

As with any serialization format, JF2 streams can potentially contain private and personally identifiable information. As such, producing and consuming implementations SHOULD take a default stance that all information in these documents are private and take steps to ensure the privacy of their users. This can include transmission only over secure connections, limiting access to streams, deletion of stored secure information, or any other steps that would apply to any private information.

13. Security Considerations

JF2 is not intended to contain executable code however, as JF2 allows arbitrary text it may be possible for publishers to craft text in an executable fashion. As such, JF2 documents should not be passed through any executable mechanism such as javascripts eval() function to be parsed. Processing of field contents should not execute any encountered code and it is recommended that any HTML formatted content be filtered to remove any executable code such as script and style tags.

JF2 documents may require privacy and integrity services depending on the document content and implementation concerns. If such services are required, they must be provided externally such as by the use of SSL/TLS connections to prevent forgery or exposure of data.

Any externally linked documents must be processed by their own format's security model. JF2 documents do not make any claims about the security of any externally referenced documents.

JF2 Streams are JSON Documents and are subject to the same security considerations described in [RFC7159].

14. IANA Considerations

14.1 The application/jf2feed+json Media Type

This specification registers the application/jf2feed+json MIME Media Type specifically for identifying documents conforming to the JF2 format with the JF2 Feed profile.

Type name: application
Subtype name: jf2feed+json
Required parameters: None
Optional parameters: None
Encoding considerations: Binary, as per [RFC6839], section 3.1; the charset parameter is not used and byte-order marks are not permitted, as per [RFC7159], sections 11 and 8.1
Security considerations: See [RFC7159] section 12 and the Security Considerations section of this specification.
Contact: Ben Roberts <ben@thatmustbe.me>

A. Change Log

A.1 Changes from 12 June 2017 WD to this version

This section lists changes from the 12 June 2017 FPWD to this version.

A.2 Changes from 28 July 2016 FPWD to 12 Jun 2017 WD

This section lists changes from the 28 July 2016 FPWD to 12 June 2017 WD

B. Acknowledgements

The authors wish to thank the Microformats, IndieWebCamp, Pump.io, and Activity Streams communities for their continued work in building the social web and helping define standards such as this one. This includes, but is certainly not limited to, Aaron Parecki, Benjamin Goering, Brent Simmons, Christopher Webber, Dave Wilkinson II, James Snell, Jonathan LaCour, Kyle Mahan, Manton Reece, Pelle Wessman, and Tantek Çelik.

C. References

C.1 Normative references

[RFC5646]
Tags for Identifying Languages. A. Phillips, Ed.; M. Davis, Ed.. IETF. September 2009. Best Current Practice. URL: https://tools.ietf.org/html/rfc5646
[RFC7159]
The JavaScript Object Notation (JSON) Data Interchange Format. T. Bray, Ed.. IETF. March 2014. Proposed Standard. URL: https://tools.ietf.org/html/rfc7159

C.2 Informative references

[HTML5]
HTML5. Ian Hickson; Robin Berjon; Steve Faulkner; Travis Leithead; Erika Doyle Navara; Theresa O'Connor; Silvia Pfeiffer. W3C. 28 October 2014. W3C Recommendation. URL: https://www.w3.org/TR/html5/
[ISO8601]
Representation of dates and times. ISO 8601:2004.. International Organization for Standardization (ISO). 2004. ISO 8601:2004. URL: http://www.iso.org/iso/catalogue_detail?csnumber=40874
[JSON-LD]
JSON-LD 1.0. Manu Sporny; Gregg Kellogg; Markus Lanthaler. W3C. 16 January 2014. W3C Recommendation. URL: https://www.w3.org/TR/json-ld/
[RFC3339]
Date and Time on the Internet: Timestamps. G. Klyne; C. Newman. IETF. July 2002. Proposed Standard. URL: https://tools.ietf.org/html/rfc3339
[RFC5988]
Web Linking. M. Nottingham. IETF. October 2010. Proposed Standard. URL: https://tools.ietf.org/html/rfc5988
[RFC6839]
Additional Media Type Structured Syntax Suffixes. T. Hansen; A. Melnikov. IETF. January 2013. Informational. URL: https://tools.ietf.org/html/rfc6839
[URL]
URL Standard. Anne van Kesteren. WHATWG. Living Standard. URL: https://url.spec.whatwg.org/
[h-card]
h-card. Tantek Çelik. http://microformats.org. Living Specification. URL: http://microformats.org/wiki/h-card
[h-entry]
h-entry. Tantek Çelik. http://microformats.org. Living Specification. URL: http://microformats.org/wiki/h-entry
[h-feed]
h-feed. Tantek Çelik. http://microformats.org. Living Specification. URL: http://microformats.org/wiki/h-feed
[jsonfeed-v1]
JSON Feed Version 1. Brent Simmons; Manton Reece. http://jsonfeed.org. Draft. URL: http://jsonfeed.org/version/1
[microformats2]
Microformats2. Tantek Çelik. http://microformats.org. Living Specification. URL: http://microformats.org/wiki/microformats2
[microformats2-parsing]
Microformats2 Parsing. Tantek Çelik. http://microformats.org. Living Specification. URL: http://microformats.org/wiki/microformats2-parsing