diff --git a/SabreTools.DatFiles/ItemDictionaryDB.cs b/SabreTools.DatFiles/ItemDictionaryDB.cs
index 669e8fe4..189c42a8 100644
--- a/SabreTools.DatFiles/ItemDictionaryDB.cs
+++ b/SabreTools.DatFiles/ItemDictionaryDB.cs
@@ -1,8 +1,8 @@
 #if NET40_OR_GREATER || NETCOREAPP
 using System.Collections.Concurrent;
-#else
-using System.Collections.Generic;
 #endif
+using System.Collections.Generic;
+using System.Linq;
 using System.Xml.Serialization;
 using Newtonsoft.Json;
 using SabreTools.DatItems;
@@ -20,30 +20,188 @@ namespace SabreTools.DatFiles
         /// <summary>
         /// Internal dictionary for all items
         /// </summary>
+        [JsonIgnore, XmlIgnore]
 #if NET40_OR_GREATER || NETCOREAPP
-        private readonly ConcurrentDictionary<long, DatItem> items = new ConcurrentDictionary<long, DatItem>();
+        private readonly ConcurrentDictionary<long, DatItem> _items = new ConcurrentDictionary<long, DatItem>();
 #else
-        private readonly Dictionary<long, DatItem> items = [];
+        private readonly Dictionary<long, DatItem> _items = [];
 #endif
 
+        /// <summary>
+        /// Current highest available item index
+        /// </summary>
+        private long _itemIndex = 0;
+
         /// <summary>
         /// Internal dictionary for all machines
         /// </summary>
+        [JsonIgnore, XmlIgnore]
 #if NET40_OR_GREATER || NETCOREAPP
-        private readonly ConcurrentDictionary<long, Machine> machines = new ConcurrentDictionary<long, Machine>();
+        private readonly ConcurrentDictionary<long, Machine> _machines = new ConcurrentDictionary<long, Machine>();
 #else
-        private readonly Dictionary<long, Machine> machines = [];
+        private readonly Dictionary<long, Machine> _machines = [];
 #endif
 
+        /// <summary>
+        /// Current highest available machine index
+        /// </summary>
+        private long _machineIndex = 0;
+
         /// <summary>
         /// Internal dictionary for item to machine mappings
         /// </summary>
+        [JsonIgnore, XmlIgnore]
 #if NET40_OR_GREATER || NETCOREAPP
-        private readonly ConcurrentDictionary<long, long> itemToMachineMapping = new ConcurrentDictionary<long, long>();
+        private readonly ConcurrentDictionary<long, long> _itemToMachineMapping = new ConcurrentDictionary<long, long>();
 #else
-        private readonly Dictionary<long, long> itemToMachineMapping = [];
+        private readonly Dictionary<long, long> _itemToMachineMapping = [];
 #endif
 
+        // TODO: Add another dictionary of string => ConcurrentList<long> representing a bucketed key to a set of item IDs
+
         #endregion
+
+        #region Fields
+
+        /// <summary>
+        /// DAT statistics
+        /// </summary>
+        [JsonIgnore, XmlIgnore]
+        public DatStatistics DatStatistics { get; } = new DatStatistics();
+
+        #endregion
+
+        #region Accessors
+
+        /// <summary>
+        /// Add an item, returning the insert index
+        /// </summary>
+        public long AddItem(DatItem item)
+        {
+            _items[_itemIndex++] = item;
+            DatStatistics.AddItemStatistics(item);
+            return _itemIndex - 1;
+        }
+
+        /// <summary>
+        /// Add a machine, returning the insert index
+        /// </summary>
+        public long AddMachine(Machine machine)
+        {
+            _machines[_machineIndex++] = machine;
+            return _machineIndex - 1;
+        }
+
+        /// <summary>
+        /// Get an item based on the index
+        /// </summary>
+        public DatItem? GetItemByIndex(long index)
+        {
+            if (!_items.ContainsKey(index))
+                return null;
+
+            return _items[index];
+        }
+
+        /// <summary>
+        /// Get a machine based on the index
+        /// </summary>
+        public Machine? GetMachineByIndex(long index)
+        {
+            if (!_machines.ContainsKey(index))
+                return null;
+
+            return _machines[index];
+        }
+
+        /// <summary>
+        /// Get the machine associated with an item index
+        /// </summary>
+        public Machine? GetMachineForItemByIndex(long itemIndex)
+        {
+            if (!_itemToMachineMapping.ContainsKey(itemIndex))
+                return null;
+
+            long machineIndex = _itemToMachineMapping[itemIndex];
+            if (!_machines.ContainsKey(machineIndex))
+                return null;
+
+            return _machines[machineIndex];
+        }
+
+        /// <summary>
+        /// Get the items associated with a machine index
+        /// </summary>
+        public DatItem[]? GetDatItemsForMachineByIndex(long machineIndex)
+        {
+            var itemIds = _itemToMachineMapping
+                .Where(mapping => mapping.Value == machineIndex)
+                .Select(mapping => mapping.Key);
+
+            var datItems = new List<DatItem>();
+            foreach (long itemId in itemIds)
+            {
+                if (_items.ContainsKey(itemId))
+                    datItems.Add(_items[itemId]);
+            }
+
+            return datItems.ToArray();
+        }
+
+        /// <summary>
+        /// Remove an item, returning if it could be removed
+        /// </summary>
+        public bool RemoveItem(long itemIndex)
+        {
+            if (!_items.ContainsKey(itemIndex))
+                return false;
+
+#if NET40_OR_GREATER || NETCOREAPP
+            _items.TryRemove(itemIndex, out _);
+#else
+            _items.Remove(itemIndex);
+#endif
+
+            if (_itemToMachineMapping.ContainsKey(itemIndex))
+#if NET40_OR_GREATER || NETCOREAPP
+                _itemToMachineMapping.TryRemove(itemIndex, out _);
+#else
+                _itemToMachineMapping.Remove(itemIndex);
+#endif
+
+            return true;
+        }
+
+        /// <summary>
+        /// Remove a machine, returning if it could be removed
+        /// </summary>
+        public bool RemoveMachine(long machineIndex)
+        {
+            if (!_machines.ContainsKey(machineIndex))
+                return false;
+
+#if NET40_OR_GREATER || NETCOREAPP
+            _machines.TryRemove(machineIndex, out _);
+#else
+            _machines.Remove(machineIndex);
+#endif
+
+            var itemIds = _itemToMachineMapping
+                .Where(mapping => mapping.Value == machineIndex)
+                .Select(mapping => mapping.Key);
+
+            foreach (long itemId in itemIds)
+            {
+#if NET40_OR_GREATER || NETCOREAPP
+                _itemToMachineMapping.TryRemove(itemId, out _);
+#else
+                _itemToMachineMapping.Remove(itemId);
+#endif
+            }
+
+            return true;
+        }
+
+#endregion
     }
 }