Routing TCP/IP, Volume 1 (2nd Edition)

Route maps are similar to access lists in that they define match criteria and an action to take in the event of a match. Route maps are different from access lists in that they not only specify match criteria but also specify set criteria. The set action can modify a route, or route a packet according to the parameters of the packet.

Policy routes are static routes that use route maps to determine which packets should be routed and where the packets should be routed.

Route tags are fields within routing information packets that allow external information to be carried through the routing domain.

Route tags have no effect on the routing protocols that carry them.