Clojurians Log v2

(let [kv (d/datalog-kv conn)]
  ;; DBI opening is idempotent, so this is safe during application startup.
  (d/open-dbi kv "audit-log")

  (d/with-transaction [cn conn]
    (let [cn-kv (d/datalog-kv cn)]
      (d/transact! cn
        [{:order/id     "o-1001"
          :order/status :order.status/paid}])

      (d/transact-kv cn-kv "audit-log"
        [[:put "o-1001"
          {:event/type :order/paid
           :order/id   "o-1001"}]]
        :string :data))))

I'm reading above example from the book, the kv store has a type called ':data' I'm wondering why don't we have an explicit datalog schema value like :db.type/data for example? (Basically an edn idoc but without need for indexing by path feature) Right now, the correct way I assume is just not to define schema at all if I want a 'arbitrary map data' as value type in the datalog store?