Motivation

Many content management systems and blogging platforms strip or sanitize RDFa attributes from user-submitted HTML, preventing the publication of structured metadata. This specification addresses this limitation by defining a namespace and conventions for escaping RDFa content.

Design Goals

• Enable RDFa embedding in restrictive HTML environments
• Maintain semantic fidelity of escaped content
• Provide clear distinction between examples and embedded data
• Support standard HTML entity escaping mechanisms

Namespace URI

The eRDFa namespace URI is:

https://escaped-rdfa.github.io/namespace/docs/1.0.html#
      

Recommended Prefix

The recommended namespace prefix is eRDFa.

Declaration in HTML

The namespace MUST be declared using the RDFa prefix attribute:

<div 
  xmlns="http://www.w3.org/1999/xhtml"
  prefix="eRDFa: https://escaped-rdfa.github.io/namespace/docs/1.0.html#
          other-namespace: http://example.com/namespace#">
  <!-- content -->
</div>
      

Escaped Declaration

When the hosting platform does not support RDFa attributes, the declaration MUST be HTML-entity escaped:

<div 
  xmlns="http://www.w3.org/1999/xhtml"
  prefix="eRDFa: https://escaped-rdfa.github.io/namespace/docs/1.0.html#
          other-namespace: http://example.com/namespace#">
  <!-- content -->
</div>
      

example

Term

eRDFa:example

Description

Indicates that the contained RDFa markup is illustrative and MUST NOT be processed as semantic data.

Usage

Applied via the rel attribute on a container element.

Processing

Processors MUST ignore all RDFa content within elements marked with rel="eRDFa:example".

<div 
  xmlns="http://www.w3.org/1999/xhtml"
  prefix="eRDFa: https://escaped-rdfa.github.io/namespace/docs/1.0.html#">
  <div rel="eRDFa:example">
    <div about="#me" vocab="http://xmlns.com/foaf/0.1/">
      <p property="name">Gregg Kellogg</p>
    </div>
  </div>
</div>
      

<div 
  xmlns="http://www.w3.org/1999/xhtml"
  prefix="eRDFa: https://escaped-rdfa.github.io/namespace/docs/1.0.html#">
  <div rel="eRDFa:example">
    <div about="#me" vocab="http://xmlns.com/foaf/0.1/">
      <p property="name">Gregg Kellogg</p>
    </div>
  </div>
</div>
      

embedded

Term

eRDFa:embedded

Description

Indicates that the contained markup is escaped RDFa that MUST be unescaped and processed as semantic data.

Usage

Applied via the rel attribute on a container element.

Processing

Processors MUST unescape HTML entities within elements marked with rel="eRDFa:embedded" and process the resulting RDFa markup.

<div 
  xmlns="http://www.w3.org/1999/xhtml"
  prefix="eRDFa: https://escaped-rdfa.github.io/namespace/docs/1.0.html#
          rss: http://purl.org/rss/1.0/
          itunes: http://www.itunes.com/dtds/podcast-1.0#">
  <div rel="eRDFa:embedded">
    <div typeof="rss:rss">
      <div rel="rss:channel">
        <div typeof="rss:item">
          <div property="rss:title" content="Episode Title"></div>
          <div property="rss:guid" content="1b593f7b-67e7-454c-bb80-32e8e32ada06"></div>
        </div>
      </div>
    </div>
  </div>
</div>
      

Processing Steps

An eRDFa processor MUST follow these steps:

1. Parse the HTML document
2. Identify elements with rel="eRDFa:example" or rel="eRDFa:embedded"
3. For eRDFa:example elements: Skip processing of contained RDFa
4. For eRDFa:embedded elements:
   1. Extract the text content
   2. Unescape HTML entities
   3. Parse the resulting markup as RDFa
   4. Extract triples according to RDFa processing rules

Escaping Rules

Content authors MUST escape the following characters using HTML entities:

Blogging Platforms

Platforms like Blogger and WordPress sanitize RDFa attributes. Authors can use eRDFa to embed podcast RSS metadata, FOAF profiles, or other structured data that survives the sanitization process.

Documentation and Examples

Technical documentation can use eRDFa:example to show RDFa markup examples without having them processed as actual metadata.

Cross-Site Scripting (XSS)

Processors MUST sanitize unescaped content to prevent XSS attacks. Script tags and event handlers within escaped content MUST be removed or neutralized before rendering.

Content Injection

Implementations SHOULD validate that unescaped content contains only valid RDFa markup and does not include malicious HTML or JavaScript.