POST /propmap/lookup/region HTTP/1.1
Host: alto.example.com
Accept: application/alto-propmap+json,application/alto-error+json
Content-Length: 132
Content-Type: application/alto-propmapparams+json

{
  "entities" : ["default-network-map.pid:pid1",
                "default-network-map.pid:pid2"],
  "properties" : [ ".region" ]
}