This link relation is defined in

It identifies a link to an OpenSearch specification. When a search link appears in a feed resource returned by the web service, it indicates that the collection is searchable. The resource referenced by the search link is an OpenSearch document describing the format of the search requests that may be submitted to search the collection. Links of this type occur in feed resources representing content items collections.

The following example shows a feed resource containing a link of this type:

<feed xmlns=""> 
    <name>Escenic Content Engine</name> 
  <link rel="self" 
  <title type="text">Content items for section with dbid="22"</title> 
  <link rel="search"