If we want syndications and newsreaders to become mainstream,  we need a clickable link  for subscribing to a syndication feed.  It must be:  

1. Vendor agnostic. No reliance on local IP addresses or private port numbers.  
2. Format agnostic. No worries about which version or RSS or Echo or NewsML it is. The feed's URI gets passed to the launched newsreader.

Two strategies come to mind:

1. Mime type. Perhaps .sub for subscription?
and/or
2. Protocol prefix. Maybe  subscribe://  

The link will point either to

• a feed's URI, or
• a list of feeds (format suggestions?).  

 ?