http://www.juniper.net/documentation/en_US/junos12.1x46/topics/reference/command-summary/show-bgp-neighbor.html
Internal BGP flags:
Aggregate Label—BGP has aggregated a set of incoming labels (labels received from the peer) into a single forwarding label.
CleanUp—The peer session is being shut down.
Delete—This peer has been deleted.
Idled—This peer has been permanently idled.
ImportEval—At the last commit operation, this peer was identified as needing to reevaluate all received routes.
Initializing—The peer session is initializing.
SendRtn—Messages are being sent to the peer.
Sync—This peer is synchronized with the rest of the peer group.
TryConnect—Another attempt is being made to connect to the peer.
Unconfigured—This peer is not configured.
WriteFailed—An attempt to write to this peer failed.
Flags Flags associated with the BGP group. This field is used by Juniper Networks customer support.
here is what I could find out.
Maybe the Exort Eval is in refeernce to exported or advertised routes