diff --git a/SabreTools.Library/DatFiles/AttractMode.cs b/SabreTools.Library/DatFiles/AttractMode.cs
index cb181f84..6410aaf8 100644
--- a/SabreTools.Library/DatFiles/AttractMode.cs
+++ b/SabreTools.Library/DatFiles/AttractMode.cs
@@ -111,6 +111,12 @@ namespace SabreTools.Library.DatFiles
             svr.Dispose();
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/ClrMamePro.cs b/SabreTools.Library/DatFiles/ClrMamePro.cs
index 260db0ad..1fd27ba6 100644
--- a/SabreTools.Library/DatFiles/ClrMamePro.cs
+++ b/SabreTools.Library/DatFiles/ClrMamePro.cs
@@ -407,6 +407,21 @@ namespace SabreTools.Library.DatFiles
             }
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[]
+            {
+                ItemType.Archive,
+                ItemType.BiosSet,
+                ItemType.Disk,
+                ItemType.Media,
+                ItemType.Release,
+                ItemType.Rom,
+                ItemType.Sample,
+            };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/DatFile.cs b/SabreTools.Library/DatFiles/DatFile.cs
index aed63cc8..8682ca80 100644
--- a/SabreTools.Library/DatFiles/DatFile.cs
+++ b/SabreTools.Library/DatFiles/DatFile.cs
@@ -2339,7 +2339,6 @@ namespace SabreTools.Library.DatFiles
 
         #endregion
 
-        // TODO: See if any of the helper methods can be broken up a bit more neatly
         #region Rebuilding and Verifying
 
         /// <summary>
@@ -3777,6 +3776,15 @@ namespace SabreTools.Library.DatFiles
             return rom;
         }
 
+        /// <summary>
+        /// Get supported types for write
+        /// </summary>
+        /// <returns>List of supported types for writing</returns>
+        protected virtual ItemType[] GetSupportedTypes()
+        {
+            return Enum.GetValues(typeof(ItemType)) as ItemType[];
+        }
+
         /// <summary>
         /// Get if an item should be ignored on write
         /// </summary>
@@ -3803,6 +3811,10 @@ namespace SabreTools.Library.DatFiles
                     return true;
             }
 
+            // If we have an item type not in the list of supported values
+            if (!GetSupportedTypes().Contains(datItem.ItemType))
+                return true;
+
             return false;
         }
 
diff --git a/SabreTools.Library/DatFiles/DosCenter.cs b/SabreTools.Library/DatFiles/DosCenter.cs
index 8daff200..e55b5792 100644
--- a/SabreTools.Library/DatFiles/DosCenter.cs
+++ b/SabreTools.Library/DatFiles/DosCenter.cs
@@ -247,6 +247,12 @@ namespace SabreTools.Library.DatFiles
             }
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/EverdriveSmdb.cs b/SabreTools.Library/DatFiles/EverdriveSmdb.cs
index 88b010ee..2d583629 100644
--- a/SabreTools.Library/DatFiles/EverdriveSmdb.cs
+++ b/SabreTools.Library/DatFiles/EverdriveSmdb.cs
@@ -83,6 +83,12 @@ namespace SabreTools.Library.DatFiles
             sr.Dispose();
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/Hashfile.cs b/SabreTools.Library/DatFiles/Hashfile.cs
index 6ba5aa4b..ce6e5437 100644
--- a/SabreTools.Library/DatFiles/Hashfile.cs
+++ b/SabreTools.Library/DatFiles/Hashfile.cs
@@ -98,6 +98,12 @@ namespace SabreTools.Library.DatFiles
             sr.Dispose();
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Disk, ItemType.Media, ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/Listrom.cs b/SabreTools.Library/DatFiles/Listrom.cs
index 3c8c9a4d..8bd57f7a 100644
--- a/SabreTools.Library/DatFiles/Listrom.cs
+++ b/SabreTools.Library/DatFiles/Listrom.cs
@@ -250,6 +250,12 @@ namespace SabreTools.Library.DatFiles
             }
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Disk, ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/Listxml.cs b/SabreTools.Library/DatFiles/Listxml.cs
index c5986adb..1a6c5cff 100644
--- a/SabreTools.Library/DatFiles/Listxml.cs
+++ b/SabreTools.Library/DatFiles/Listxml.cs
@@ -1126,6 +1126,34 @@ namespace SabreTools.Library.DatFiles
             }
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[]
+            {
+                ItemType.Adjuster,
+                ItemType.BiosSet,
+                ItemType.Chip,
+                ItemType.Condition,
+                ItemType.Configuration,
+                ItemType.Device,
+                ItemType.DeviceReference,
+                ItemType.DipSwitch,
+                ItemType.Disk,
+                ItemType.Display,
+                ItemType.Driver,
+                ItemType.Feature,
+                ItemType.Input,
+                ItemType.Port,
+                ItemType.RamOption,
+                ItemType.Rom,
+                ItemType.Sample,
+                ItemType.Slot,
+                ItemType.SoftwareList,
+                ItemType.Sound,
+            };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/Logiqx.cs b/SabreTools.Library/DatFiles/Logiqx.cs
index b0ab9cec..9106277a 100644
--- a/SabreTools.Library/DatFiles/Logiqx.cs
+++ b/SabreTools.Library/DatFiles/Logiqx.cs
@@ -658,6 +658,21 @@ namespace SabreTools.Library.DatFiles
             }
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[]
+            {
+                ItemType.Archive,
+                ItemType.BiosSet,
+                ItemType.Disk,
+                ItemType.Media,
+                ItemType.Release,
+                ItemType.Rom,
+                ItemType.Sample,
+            };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/OfflineList.cs b/SabreTools.Library/DatFiles/OfflineList.cs
index cc994a9b..cbf4b632 100644
--- a/SabreTools.Library/DatFiles/OfflineList.cs
+++ b/SabreTools.Library/DatFiles/OfflineList.cs
@@ -654,6 +654,12 @@ namespace SabreTools.Library.DatFiles
             return roms;
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/OpenMSX.cs b/SabreTools.Library/DatFiles/OpenMSX.cs
index b66eb367..08ca3de5 100644
--- a/SabreTools.Library/DatFiles/OpenMSX.cs
+++ b/SabreTools.Library/DatFiles/OpenMSX.cs
@@ -508,6 +508,12 @@ namespace SabreTools.Library.DatFiles
             return null;
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/RomCenter.cs b/SabreTools.Library/DatFiles/RomCenter.cs
index 586281ba..0b562dbe 100644
--- a/SabreTools.Library/DatFiles/RomCenter.cs
+++ b/SabreTools.Library/DatFiles/RomCenter.cs
@@ -361,6 +361,12 @@ namespace SabreTools.Library.DatFiles
             }
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/SeparatedValue.cs b/SabreTools.Library/DatFiles/SeparatedValue.cs
index d24cc679..4b50af37 100644
--- a/SabreTools.Library/DatFiles/SeparatedValue.cs
+++ b/SabreTools.Library/DatFiles/SeparatedValue.cs
@@ -99,6 +99,12 @@ namespace SabreTools.Library.DatFiles
             svr.Dispose();
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[] { ItemType.Disk, ItemType.Media, ItemType.Rom };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>
diff --git a/SabreTools.Library/DatFiles/SoftwareList.cs b/SabreTools.Library/DatFiles/SoftwareList.cs
index be617922..294a9d7d 100644
--- a/SabreTools.Library/DatFiles/SoftwareList.cs
+++ b/SabreTools.Library/DatFiles/SoftwareList.cs
@@ -500,6 +500,19 @@ namespace SabreTools.Library.DatFiles
             }
         }
 
+        /// <inheritdoc/>
+        protected override ItemType[] GetSupportedTypes()
+        {
+            return new ItemType[]
+            {
+                ItemType.DipSwitch,
+                ItemType.Disk,
+                ItemType.Info,
+                ItemType.Rom,
+                ItemType.SharedFeature,
+            };
+        }
+
         /// <summary>
         /// Create and open an output file for writing direct from a dictionary
         /// </summary>