diff --git a/.eslintrc b/.eslintrc
index b0791eea..340ba6a7 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -28,6 +28,7 @@
     "Operation": true,
     "getRandom": true,
     "RBTree": true,
-    "compareIds": true
+    "compareIds": true,
+    "EventHandler": true
   }
 }
diff --git a/src/OperationStore.js b/src/OperationStore.js
index 1190c7c1..d2c3a1c5 100644
--- a/src/OperationStore.js
+++ b/src/OperationStore.js
@@ -9,7 +9,7 @@ class AbstractTransaction { //eslint-disable-line no-unused-vars
     if (t == null) {
       var op = yield* this.getOperation(id);
       if (op != null) {
-        t = yield* Y[op.type].create(this.store, op.id);
+        t = yield* Y[op.type].create(this.store, op);
         this.store.initializedTypes[sid] = t;
       }
     }
@@ -36,6 +36,18 @@ class AbstractTransaction { //eslint-disable-line no-unused-vars
       throw new Error("Operations must arrive in order!");
     }
   }
+  *applyCreatedOperations (ops) {
+    var send = [];
+    for (var i = 0; i < ops.length; i++) {
+      var op = ops[i];
+      yield* Struct[op.struct].execute.call(this, op);
+      send.push(Struct[op.struct].encode(op));
+    }
+    this.store.y.connector.broadcast({
+      type: "update",
+      ops: send
+    });
+  }
 }
 
 type Listener = {
@@ -70,6 +82,13 @@ class AbstractOperationStore { //eslint-disable-line no-unused-vars
   }
   setUserId (userId) {
     this.userId = userId;
+    this.opClock = 0;
+  }
+  getNextOpId () {
+    if (this.userId == null) {
+      throw new Error("OperationStore not yet initialized!");
+    }
+    return [this.userId, this.opClock++];
   }
   apply (ops) {
     for (var key in ops) {
diff --git a/src/OperationStores/Memory.js b/src/OperationStores/Memory.js
index 353c8103..5f921ff9 100644
--- a/src/OperationStores/Memory.js
+++ b/src/OperationStores/Memory.js
@@ -14,13 +14,12 @@ function copyObject (o) {
 }
 
 type StateVector = Array<State>;
-type OperationSet = Object; // os[Id] = op
 type StateSet = Object;
 
 Y.Memory = (function(){ //eslint-disable-line no-unused-vars
   class Transaction extends AbstractTransaction { //eslint-disable-line
     ss: StateSet;
-    os: OperationSet;
+    os: RBTree;
     store: OperationStore;
 
     constructor (store : OperationStore) {
diff --git a/src/Struct.js b/src/Struct.js
index 64c9e990..1d2fc8a0 100644
--- a/src/Struct.js
+++ b/src/Struct.js
@@ -35,28 +35,12 @@ function compareIds(id1, id2) {
 }
 
 var Struct = {
-  Operation: {  //eslint-disable-line no-unused-vars
-    create: function*(op : Op) : Struct.Operation {
-      var user = this.store.y.connector.userId;
-      var state = yield* this.getState(user);
-      op.id = [user, state.clock];
-      yield* Struct[op.struct].execute.call(this, op);
-
-      this.store.y.connector.broadcast({
-        type: "update",
-        ops: [Struct[op.struct].encode(op)]
-      });
-      return op;
-    }
-  },
+  /*
+  {
+  target: Id
+  }
+  */
   Delete: {
-    create: function* (op) {
-      if (op.target == null) {
-        throw new Error("You must define a delete target!");
-      }
-      op.struct = "Delete";
-      return yield* Struct.Operation.create.call(this, op);
-    },
     encode: function (op) {
       return op;
     },
@@ -77,20 +61,12 @@ var Struct = {
         content: any,
         left: Id,
         right: Id,
+        origin: id,
         parent: Id,
-        parentSub: string (optional)
+        parentSub: string (optional),
+        id: this.os.getNextOpId()
       }
     */
-    create: function* ( op: Op ) : Insert {
-      if ( op.left === undefined
-        || op.right === undefined
-        || op.parent === undefined ) {
-          throw new Error("You must define left, right, and parent!");
-        }
-      op.origin = op.left;
-      op.struct = "Insert";
-      return yield* Struct.Operation.create.call(this, op);
-    },
     encode: function(op){
       /*var e = {
         id: op.id,
@@ -248,12 +224,15 @@ var Struct = {
     }
   },
   List: {
-    create: function* ( op : Op){
-      op.start = null;
-      op.end = null;
-      op.struct = "List";
-      return yield* Struct.Operation.create.call(this, op);
-    },
+    /*
+    {
+      start: null,
+      end: null,
+      struct: "List",
+      type: "",
+      id: this.os.getNextOpId()
+    }
+    */
     encode: function(op){
       return {
         struct: "List",
@@ -315,7 +294,7 @@ var Struct = {
       while ( o != null) {
         var operation = yield* this.getOperation(o);
         if (!operation.deleted) {
-          res.push(f(operation.content));
+          res.push(f(operation));
         }
         o = operation.right;
       }
@@ -350,19 +329,18 @@ var Struct = {
   Map: {
     /*
       {
-        // empty
+        map: {},
+        struct: "Map",
+        type: "",
+        id: this.os.getNextOpId()
       }
     */
-    create: function* ( op : Op ){
-      op.map = {};
-      op.struct = "Map";
-      return yield* Struct.Operation.create.call(this, op);
-    },
     encode: function(op){
       return {
         struct: "Map",
         type: op.type,
-        id: op.id
+        id: op.id,
+        map: {} // overwrite map!!
       };
     },
     requiredOps: function(){
diff --git a/src/Types/Array.js b/src/Types/Array.js
new file mode 100644
index 00000000..bbb254d4
--- /dev/null
+++ b/src/Types/Array.js
@@ -0,0 +1,109 @@
+
+
+(function(){
+
+  class YArray {
+    constructor (os, _model, idArray, valArray) {
+      this.os = os;
+      this._model = _model;
+      // Array of all the operation id's
+      this.idArray = idArray;
+      this.valArray = valArray;
+      this.eventHandler = new EventHandler( ops =>{
+        for (var i in ops) {
+          var op = ops[i];
+          var pos;
+          if (op.right === null) {
+            pos = this.idArray.length;
+          } else {
+            var sid = JSON.stringify(op.right);
+            pos = this.idArray.indexOf(sid);
+          }
+          if (pos < 0) {
+            throw new Error("Unexpected operation!");
+          }
+          this.idArray.splice(pos, 0, JSON.stringify(op.id));
+          this.valArray.splice(pos, 0, op.content);
+        }
+      });
+    }
+    get (pos) {
+      if (pos == null || typeof pos !== "number") {
+          throw new Error("pos must be a number!");
+      }
+      return this.valArray[pos];
+    }
+    toArray() {
+      return this.valArray.slice();
+    }
+    insert (pos, contents) {
+      if (typeof pos !== "number") {
+        throw new Error("pos must be a number!");
+      }
+      if (!(contents instanceof Array)) {
+        throw new Error("contents must be an Array of objects!");
+      }
+      if (contents.length === 0) {
+        return;
+      }
+      if (pos > this.idArray.length || pos < 0) {
+        throw new Error("This position exceeds the range of the array!");
+      }
+      var mostLeft = pos === 0 ? null : JSON.parse(this.idArray[pos - 1]);
+      var mostRight = pos === this.idArray.length ? null : JSON.parse(this.idArray[pos]);
+
+      var ops = [];
+      var prevId = mostLeft;
+      for (var i = 0; i < contents.length; i++) {
+        var op = {
+          left: prevId,
+          origin: prevId,
+          right: mostRight,
+          parent: this._model,
+          content: contents[i],
+          struct: "Insert",
+          id: this.os.getNextOpId()
+        };
+        ops.push(op);
+        prevId = op.id;
+      }
+      var eventHandler = this.eventHandler;
+      eventHandler.awaitAndPrematurelyCall(ops);
+      this.os.requestTransaction(function*(){
+        yield* this.applyCreatedOperations(ops);
+        eventHandler.awaitedLastOp(ops.length);
+      });
+    }
+    *delete (pos) {
+      if (typeof pos !== "number") {
+        throw new Error("pos must be a number!");
+      }
+      var t = yield "transaction";
+      var model = yield* t.getOperation(this._model);
+      yield* Y.Struct.Array.delete.call(t, model, pos);
+    }
+    _changed (op) {
+      this.eventHandler.receivedOp(op);
+    }
+  }
+
+  Y.Array = function* _YArray(){
+    var model = {
+      start: null,
+      end: null,
+      struct: "List",
+      type: "Array",
+      id: this.store.getNextOpId()
+    };
+    yield* this.applyCreatedOperations([model]);
+    return yield* this.createType(model);
+  };
+  Y.Array.create = function* YArrayCreate(os, model){
+    var valArray = [];
+    var idArray = yield* Y.Struct.List.map.call(this, model, function(c){
+      valArray.push(c.content);
+      return JSON.stringify(c.id);
+    });
+    return new YArray(os, model.id, idArray, valArray);
+  };
+})();
diff --git a/src/Types/List.js b/src/Types/List.js
deleted file mode 100644
index 990d100a..00000000
--- a/src/Types/List.js
+++ /dev/null
@@ -1,48 +0,0 @@
-
-
-(function(){
-
-  class List {
-    constructor (_model) {
-      this._model = _model;
-    }
-    *val (pos) {
-      var t = yield "transaction";
-      var model = yield* t.getOperation(this._model);
-      if (pos != null) {
-        var o = yield* Y.Struct.List.ref.call(t, model, pos);
-        return o ? o.content : null;
-      } else {
-        return yield* Y.Struct.List.map.call(t, model, function(c){return c; });
-      }
-    }
-    *insert (pos, contents) {
-      if (typeof pos !== "number") {
-        throw new Error("pos must be a number!");
-      }
-      if (!(contents instanceof Array)) {
-        throw new Error("contents must be an Array of objects!");
-      }
-      var t = yield "transaction";
-      var model = yield* t.getOperation(this._model);
-      yield* Y.Struct.List.insert.call(t, model, pos, contents);
-    }
-    *delete (pos) {
-      if (typeof pos !== "number") {
-        throw new Error("pos must be a number!");
-      }
-      var t = yield "transaction";
-      var model = yield* t.getOperation(this._model);
-      yield* Y.Struct.List.delete.call(t, model, pos);
-    }
-    _changed () {
-    }
-  }
-
-  Y.List = function* YList(){
-    var t = yield "transaction";
-    var model = yield* Y.Struct.List.create.call(t, {type: "List"});
-    return t.createType(model);
-  };
-  Y.List.Create = List;
-})();
diff --git a/src/Types/Map.js b/src/Types/Map.js
index 47482692..62115f53 100644
--- a/src/Types/Map.js
+++ b/src/Types/Map.js
@@ -14,25 +14,29 @@ class EventHandler {
       this.waiting.push(copyObject(op));
     }
   }
-  awaitAndPrematurelyCall (op) {
+  awaitAndPrematurelyCall (ops) {
     this.awaiting++;
-    this.onevent([op]);
+    this.onevent(ops);
   }
-  awaitedLastOp () {
-    var op = this.waiting.pop();
-    for (var i = this.waiting.length - 1; i >= 0; i--) {
-      var w = this.waiting[i];
-      if (compareIds(op.left, w.id)) {
-        // include the effect of op in w
-        w.right = op.id;
-        // exclude the effect of w in op
-        op.left = w.left;
-      } else if (compareIds(op.right, w.id)) {
-        // similar..
-        w.left = op.id;
-        op.right = w.right;
+  awaitedLastOp (n) {
+    var ops = this.waiting.splice(this.waiting.length - n);
+    for (var oid = 0; oid < ops.length; oid++) {
+      var op = ops[oid];
+      for (var i = this.waiting.length - 1; i >= 0; i--) {
+        var w = this.waiting[i];
+        if (compareIds(op.left, w.id)) {
+          // include the effect of op in w
+          w.right = op.id;
+          // exclude the effect of w in op
+          op.left = w.left;
+        } else if (compareIds(op.right, w.id)) {
+          // similar..
+          w.left = op.id;
+          op.right = w.right;
+        }
       }
     }
+
     this.awaiting--;
     if (this.awaiting <= 0) {
       var events = this.waiting;
@@ -87,8 +91,10 @@ class EventHandler {
       var insert = {
         left: null,
         right: right,
+        origin: null,
         parent: this._model,
-        parentSub: key
+        parentSub: key,
+        struct: "Insert"
       };
       var def = Promise.defer();
       if ( value != null && value.constructor === GeneratorFunction) {
@@ -96,17 +102,19 @@ class EventHandler {
         this.os.requestTransaction(function*(){
           var type = yield* value.call(this);
           insert.opContent = type._model;
-          yield* Struct.Insert.create.call(this, insert);
+          insert.id = this.store.getNextOpId();
+          yield* this.applyCreatedOperations([insert]);
           def.resolve(type);
         });
       } else {
         insert.content = value;
+        insert.id = this.os.getNextOpId();
         var eventHandler = this.eventHandler;
-        eventHandler.awaitAndPrematurelyCall(insert);
+        eventHandler.awaitAndPrematurelyCall([insert]);
 
         this.os.requestTransaction(function*(){
-          yield* Struct.Insert.create.call(this, insert);
-          eventHandler.awaitedLastOp();
+          yield* this.applyCreatedOperations([insert]);
+          eventHandler.awaitedLastOp(1);
         });
         def.resolve(value);
       }
@@ -124,7 +132,13 @@ class EventHandler {
   }
 
   Y.Map = function* YMap(){
-    var model = yield* Y.Struct.Map.create.call(this, {type: "Map"});
+    var model = {
+      map: {},
+      struct: "Map",
+      type: "Map",
+      id: this.store.getNextOpId()
+    };
+    yield* this.applyCreatedOperations([model]);
     return yield* this.createType(model);
   };
   Y.Map.create = function* YMapCreate(os, model){
diff --git a/src/y.spec.js b/src/y.spec.js
index ef2796e7..06381c55 100644
--- a/src/y.spec.js
+++ b/src/y.spec.js
@@ -21,9 +21,9 @@ function getRandomNumber(n) {
   return Math.floor(Math.random() * n);
 }
 
-var numberOfYMapTests = 30;
+var numberOfYMapTests = 5;
 
-function applyRandomTransactions (users, transactions, numberOfTransactions) {
+function applyRandomTransactions (users, objects, transactions, numberOfTransactions) {
   function randomTransaction (root) {
     var f = getRandom(transactions);
     f(root);
@@ -34,7 +34,7 @@ function applyRandomTransactions (users, transactions, numberOfTransactions) {
       // 10% chance to flush
       users[0].connector.flushOne();
     } else {
-      randomTransaction(getRandom(users).root);
+      randomTransaction(getRandom(objects));
     }
   }
 }
@@ -70,7 +70,7 @@ function compareAllUsers(users){
 }
 
 describe("Yjs", function(){
-  jasmine.DEFAULT_TIMEOUT_INTERVAL = 500;
+  jasmine.DEFAULT_TIMEOUT_INTERVAL = 3000;
   beforeEach(function(done){
     if (this.users != null) {
       for (var y of this.users) {
@@ -121,6 +121,16 @@ describe("Yjs", function(){
         done();
       });
     });
+    it("Map can set custom types (Array)", function(done){
+      var y = this.users[0].root;
+      y.set("Array", Y.Array).then(function(array) {
+        array.insert(0, [1, 2, 3]);
+        return y.get("Array");
+      }).then(function(array){
+        expect(array.toArray()).toEqual([1, 2, 3]);
+        done();
+      });
+    });
     it("Basic get&set of Map property (converge via update)", function(done){
       var u = this.users[0];
       u.connector.flushAll();
@@ -172,6 +182,28 @@ describe("Yjs", function(){
         done();
       }, 50);
     });
+    it("Basic insert in array (handle three conflicts)", function(done){
+      var y = this.users[0];
+      var l1, l2, l3;
+      y.root.set("Array", Y.Array).then((array)=>{
+        l1 = array;
+        y.connector.flushAll();
+        l1.insert(0, [0]);
+        return this.users[1].root.get("Array");
+      }).then((array)=>{
+        l2 = array;
+        l2.insert(0, [1]);
+        return this.users[2].root.get("Array");
+      }).then((array)=>{
+        l3 = array;
+        l3.insert(0, [2]);
+        y.connector.flushAll();
+        expect(l1.toArray()).toEqual(l2.toArray());
+        expect(l2.toArray()).toEqual(l3.toArray());
+        compareAllUsers(this.users);
+        done();
+      });
+    });
   });
   describe("Map random tests", function(){
     var randomMapTransactions = [
@@ -182,10 +214,10 @@ describe("Yjs", function(){
         map.delete("somekey");
       }
     ];
-    function compareMapValues(users){
+    function compareMapValues(maps){
       var firstMap;
-      for (var u of users) {
-        var val = u.root.get();
+      for (var map of maps) {
+        var val = map.get();
         if (firstMap == null) {
           firstMap = val;
         } else {
@@ -193,79 +225,80 @@ describe("Yjs", function(){
         }
       }
     }
-    it(`succeed after ${numberOfYMapTests} actions with flush before transactions`, function(done){
+    beforeEach(function(done){
+      this.users[0].root.set("Map", Y.Map);
       this.users[0].connector.flushAll();
-      applyRandomTransactions(this.users, randomMapTransactions, numberOfYMapTests);
-      setTimeout(()=>{
-        compareAllUsers(this.users);
-        compareMapValues(this.users);
+
+      var then = Promise.resolve();
+      var maps = [];
+      for (var u of this.users) {
+        then = then.then(function(){ //eslint-disable-line
+          return u.root.get("Map");
+        }).then(function(map){//eslint-disable-line
+          maps.push(map);
+        });
+      }
+      this.maps = maps;
+      then.then(function(){
         done();
-      }, 500);
+      });
     });
-    it(`succeed after ${numberOfYMapTests} actions without flush before transactions`, function(done){
-      applyRandomTransactions(this.users, randomMapTransactions, numberOfYMapTests);
+    it(`succeed after ${numberOfYMapTests} actions`, function(done){
+      applyRandomTransactions(this.users, this.maps, randomMapTransactions, numberOfYMapTests);
       setTimeout(()=>{
         compareAllUsers(this.users);
-        compareMapValues(this.users);
+        compareMapValues(this.maps);
         done();
       }, 500);
     });
   });
 
-/*
-
-  var numberOfYListTests = 100;
-  describe("List random tests", function(){
-    var randomListTests = [function* insert (root) {
-      var list = yield* root.get("list");
-      yield* list.insert(Math.floor(Math.random() * 10), [getRandomNumber()]);
-    }, function* delete_(root) {
-      var list = yield* root.get("list");
-      yield* list.delete(Math.floor(Math.random() * 10));
-    }];
-    beforeEach(function(){
-      this.users[0].transact(function*(root){
-        var list = yield* Y.List();
-        yield* root.set("list", list);
-      });
-      this.users[0].connector.flushAll();
-    });
-
-    it(`succeeds after ${numberOfYListTests} actions`, function(){
-      applyRandomTransactions(this.users, randomListTests, numberOfYListTests);
-      compareAllUsers(this.users);
-      var userList;
-      this.users[0].transact(function*(root){
-        var list = yield* root.get("list");
-        if (userList == null) {
-          userList = yield* list.get();
+  var numberOfYArrayTests = 10;
+  describe("Array random tests", function(){
+    var randomMapTransactions = [
+      function insert (array) {
+        array.insert(getRandomNumber(array.toArray().length), [getRandomNumber()]);
+      }
+    ];
+    function compareArrayValues(arrays){
+      var firstArray;
+      for (var l of arrays) {
+        var val = l.toArray();
+        if (firstArray == null) {
+          firstArray = val;
         } else {
-          expect(userList).toEqual(yield* list.get());
-          expect(userList.length > 0).toBeTruthy();
+          expect(val).toEqual(firstArray);
         }
-      });
-    });
-  });
+      }
+    }
+    beforeEach(function(done){
+      this.users[0].root.set("Array", Y.Array);
+      this.users[0].connector.flushAll();
 
-  describe("Map debug tests", function(){
-    beforeEach(function(){
-      this.u1 = this.users[0];
-      this.u2 = this.users[1];
-      this.u3 = this.users[2];
-    });
-    it("concurrent insertions #1", function(){
-      this.u1.transact(function*(root){
-        var op = {
-          content: 1,
-          left: null,
-          right: null,
-          parent: root._model,
-          parentSub: "a"
-        };
-        Struct.Insert.create.call(this, op);
+      var then = Promise.resolve();
+      var arrays = [];
+      for (var u of this.users) {
+        then = then.then(function(){ //eslint-disable-line
+          return u.root.get("Array");
+        }).then(function(array){//eslint-disable-line
+          arrays.push(array);
+        });
+      }
+      this.arrays = arrays;
+      then.then(function(){
+        done();
       });
-      compareAllUsers(this.users);
+    });
+    it("arrays.length equals users.length", function(){
+      expect(this.arrays.length).toEqual(this.users.length);
+    });
+    it(`succeed after ${numberOfYArrayTests} actions`, function(done){
+      applyRandomTransactions(this.users, this.arrays, randomMapTransactions, numberOfYArrayTests);
+      setTimeout(()=>{
+        compareAllUsers(this.users);
+        compareArrayValues(this.arrays);
+        done();
+      }, 500);
     });
   });
-  */
 });