The objective of Simple Sharing Extensions (SSE) is to define the minimum extensions necessary to enable loosely-cooperating apps:

1. to use RSS as the basis for item sharing – that is, the bi-directional, asynchronous replication of new and changed items amongst two or more cross-subscribed feeds.
2. to use OPML as the basis for outline sharing – that is, the bi-directional, asynchronous replication of outlines, such as RSS aggregators subscription lists - from Microsoft