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   <body>
     <section id="abstract">
       <p>
-This specification describes mechanisms that can be used to represent a
+This specification describes an <em>extension mechanism</em> for the
+Verifiable Credential Data Model, that can be used to represent a
 Verifiable Credential through a visual, auditory, or haptic medium. It covers
 rendering a Verifiable Credential to a physical document, digital image,
 screen reader, or braille output.
