When OpenConfig is enabled, the entire YANG tree is exposed to the client. This allows a client to have read and write access to all parts of the YANG tree. In some cases, it would be preferable to block portions of the YANG tree so that specific part of the tree cannot be modified or read by the client. 

The candidate configuration feature implements support for a candidate data store as specified in RFC6241.

When this feature is enabled, responses to gNMI get requests as well as NETCONF get-config responses will contain the default values for YANG leafs if those leafs do not have any other value. This means that where a leaf value would normally be returned in a response, its default value (as defined in the YANG model) will be returned if the leaf does not have any other value assigned to it. Before this change, leafs that had a default value would not have been included in gNMI get responses.