diff --git a/source/reference/api/start.txt b/source/reference/api/start.txt
index 828e28215..9a4a27142 100644
--- a/source/reference/api/start.txt
+++ b/source/reference/api/start.txt
@@ -228,6 +228,9 @@ The ``sharding`` option has the following parameters:
      - Optional. Sets whether sync creates a supporting index 
        for the shard key, if none exists.  Defaults to ``false``.
 
+       For more information and limitations, see 
+       :ref:`c2c-supporting-index-behavior`.
+
    * - ``shardingEntries``
      - array of documents
      - Required. Sets the namespace and key of collections to shard 
@@ -383,6 +386,8 @@ collections.
 The ``sharding.shardingEntries`` array specifies the collections to shard.
 Collections that are not listed in this array replicate as unsharded.
 
+.. _c2c-supporting-index-behavior:
+
 Supporting Indexes
 ~~~~~~~~~~~~~~~~~~