diff --git a/SabreTools.Filter/FilterParser.cs b/SabreTools.Filter/FilterParser.cs
index e71d1073..b5cd43f0 100644
--- a/SabreTools.Filter/FilterParser.cs
+++ b/SabreTools.Filter/FilterParser.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using System.Reflection;
+using SabreTools.Models;
 using SabreTools.Models.Internal;
 
 namespace SabreTools.Filter
@@ -55,16 +56,8 @@ namespace SabreTools.Filter
             if (constantMatch == null)
                 return (null, null);
 
-            // Filter out fields that can't be matched on
-            return constantMatch switch
-            {
-                Header.CanOpenKey => (null, null),
-                Header.ImagesKey => (null, null),
-                Header.InfosKey => (null, null),
-                Header.NewDatKey => (null, null),
-                Header.SearchKey => (null, null),
-                _ => (MetadataFile.HeaderKey, constantMatch),
-            };
+            // Return the sanitized ID
+            return (MetadataFile.HeaderKey, constantMatch);
         }
 
         /// <summary>
@@ -82,46 +75,13 @@ namespace SabreTools.Filter
             if (constantMatch == null)
                 return (null, null);
 
-            // Filter out fields that can't be matched on
-            return constantMatch switch
-            {
-                Machine.AdjusterKey => (null, null),
-                Machine.ArchiveKey => (null, null),
-                Machine.BiosSetKey => (null, null),
-                Machine.ChipKey => (null, null),
-                Machine.ConfigurationKey => (null, null),
-                Machine.ControlKey => (null, null),
-                Machine.DeviceKey => (null, null),
-                Machine.DeviceRefKey => (null, null),
-                Machine.DipSwitchKey => (null, null),
-                Machine.DiskKey => (null, null),
-                Machine.DisplayKey => (null, null),
-                Machine.DriverKey => (null, null),
-                Machine.DumpKey => (null, null),
-                Machine.FeatureKey => (null, null),
-                Machine.InfoKey => (null, null),
-                Machine.InputKey => (null, null),
-                Machine.MediaKey => (null, null),
-                Machine.PartKey => (null, null),
-                Machine.PortKey => (null, null),
-                Machine.RamOptionKey => (null, null),
-                Machine.ReleaseKey => (null, null),
-                Machine.RomKey => (null, null),
-                Machine.SampleKey => (null, null),
-                Machine.SharedFeatKey => (null, null),
-                Machine.SlotKey => (null, null),
-                Machine.SoftwareListKey => (null, null),
-                Machine.SoundKey => (null, null),
-                Machine.TruripKey => (null, null),
-                Machine.VideoKey => (null, null),
-                _ => (MetadataFile.MachineKey, constantMatch),
-            };
+            // Return the sanitized ID
+            return (MetadataFile.MachineKey, constantMatch);
         }
 
         /// <summary>
         /// Get constant values for the given type, if possible
         /// </summary>
-        /// <remarks>TODO: Create a NoFilter attribute for non-mappable filter IDs</remarks>
         private static string[]? GetConstants(Type? type)
         {
             if (type == null)
@@ -133,6 +93,7 @@ namespace SabreTools.Filter
 
             return fields
                 .Where(f => f.IsLiteral && !f.IsInitOnly)
+                .Where(f => f.CustomAttributes.Any(a => a.AttributeType == typeof(NoFilterAttribute)))
                 .Select(f => f.GetRawConstantValue() as string)
                 .Where(v => v != null)
                 .ToArray()!;
diff --git a/SabreTools.Models/Internal/Adjuster.cs b/SabreTools.Models/Internal/Adjuster.cs
index e48aa708..77014dcb 100644
--- a/SabreTools.Models/Internal/Adjuster.cs
+++ b/SabreTools.Models/Internal/Adjuster.cs
@@ -9,6 +9,7 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         // <remarks>Condition</remarks>
+        [NoFilter]
         public const string ConditionKey = "condition";
 
         /// <remarks>bool</remarks>
diff --git a/SabreTools.Models/Internal/ConfSetting.cs b/SabreTools.Models/Internal/ConfSetting.cs
index 6f24d52d..756e3743 100644
--- a/SabreTools.Models/Internal/ConfSetting.cs
+++ b/SabreTools.Models/Internal/ConfSetting.cs
@@ -9,6 +9,7 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Condition</remarks>
+        [NoFilter]
         public const string ConditionKey = "condition";
 
         /// <remarks>(yes|no) "no"</remarks>
diff --git a/SabreTools.Models/Internal/Configuration.cs b/SabreTools.Models/Internal/Configuration.cs
index be432faf..ab6da749 100644
--- a/SabreTools.Models/Internal/Configuration.cs
+++ b/SabreTools.Models/Internal/Configuration.cs
@@ -9,12 +9,15 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Condition</remarks>
+        [NoFilter]
         public const string ConditionKey = "condition";
 
         /// <remarks>ConfLocation[]</remarks>
+        [NoFilter]
         public const string ConfLocationKey = "conflocation";
 
         /// <remarks>ConfSetting[]</remarks>
+        [NoFilter]
         public const string ConfSettingKey = "confsetting";
 
         /// <remarks>string</remarks>
diff --git a/SabreTools.Models/Internal/DataArea.cs b/SabreTools.Models/Internal/DataArea.cs
index 3d592189..49325ce8 100644
--- a/SabreTools.Models/Internal/DataArea.cs
+++ b/SabreTools.Models/Internal/DataArea.cs
@@ -15,6 +15,7 @@ namespace SabreTools.Models.Internal
         public const string NameKey = "name";
 
         /// <remarks>Rom[]</remarks>
+        [NoFilter]
         public const string RomKey = "rom";
 
         /// <remarks>long</remarks>
diff --git a/SabreTools.Models/Internal/Device.cs b/SabreTools.Models/Internal/Device.cs
index abfdec1b..e1732eba 100644
--- a/SabreTools.Models/Internal/Device.cs
+++ b/SabreTools.Models/Internal/Device.cs
@@ -9,12 +9,14 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Extension[]</remarks>
+        [NoFilter]
         public const string ExtensionKey = "extension";
 
         /// <remarks>string</remarks>
         public const string FixedImageKey = "fixed_image";
 
         /// <remarks>Instance</remarks>
+        [NoFilter]
         public const string InstanceKey = "instance";
 
         /// <remarks>string</remarks>
diff --git a/SabreTools.Models/Internal/DipSwitch.cs b/SabreTools.Models/Internal/DipSwitch.cs
index 9bad17b3..41b8f1f5 100644
--- a/SabreTools.Models/Internal/DipSwitch.cs
+++ b/SabreTools.Models/Internal/DipSwitch.cs
@@ -9,15 +9,18 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Condition</remarks>
+        [NoFilter]
         public const string ConditionKey = "condition";
 
         /// <remarks>(yes|no) "no"</remarks>
         public const string DefaultKey = "default";
 
         /// <remarks>DipLocation[]</remarks>
+        [NoFilter]
         public const string DipLocationKey = "diplocation";
 
         /// <remarks>DipValue[]</remarks>
+        [NoFilter]
         public const string DipValueKey = "dipvalue";
 
         /// <remarks>string[]</remarks>
diff --git a/SabreTools.Models/Internal/DipValue.cs b/SabreTools.Models/Internal/DipValue.cs
index a0b75459..7bf27357 100644
--- a/SabreTools.Models/Internal/DipValue.cs
+++ b/SabreTools.Models/Internal/DipValue.cs
@@ -9,6 +9,7 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Condition</remarks>
+        [NoFilter]
         public const string ConditionKey = "condition";
 
         /// <remarks>(yes|no) "no"</remarks>
diff --git a/SabreTools.Models/Internal/DiskArea.cs b/SabreTools.Models/Internal/DiskArea.cs
index d8f7f40c..5f4420ef 100644
--- a/SabreTools.Models/Internal/DiskArea.cs
+++ b/SabreTools.Models/Internal/DiskArea.cs
@@ -9,6 +9,7 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Disk[]</remarks>
+        [NoFilter]
         public const string DiskKey = "disk";
 
         /// <remarks>string</remarks>
diff --git a/SabreTools.Models/Internal/Dump.cs b/SabreTools.Models/Internal/Dump.cs
index 12bd685c..d3d52e29 100644
--- a/SabreTools.Models/Internal/Dump.cs
+++ b/SabreTools.Models/Internal/Dump.cs
@@ -9,15 +9,19 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Rom</remarks>
+        [NoFilter]
         public const string MegaRomKey = "megarom";
 
         /// <remarks>Original</remarks>
+        [NoFilter]
         public const string OriginalKey = "original";
 
         /// <remarks>Rom</remarks>
+        [NoFilter]
         public const string RomKey = "rom";
 
         /// <remarks>Rom</remarks>
+        [NoFilter]
         public const string SCCPlusCartKey = "sccpluscart";
 
         #endregion
diff --git a/SabreTools.Models/Internal/Header.cs b/SabreTools.Models/Internal/Header.cs
index bf06312a..a5bdb76f 100644
--- a/SabreTools.Models/Internal/Header.cs
+++ b/SabreTools.Models/Internal/Header.cs
@@ -18,6 +18,7 @@ namespace SabreTools.Models.Internal
 
         /// TODO: This needs an internal model OR mapping to fields
         /// <remarks>CanOpen</remarks>
+        [NoFilter]
         public const string CanOpenKey = "canOpen";
 
         /// <remarks>string</remarks>
@@ -67,6 +68,7 @@ namespace SabreTools.Models.Internal
 
         /// TODO: This needs an internal model OR mapping to fields
         /// <remarks>Search</remarks>
+        [NoFilter]
         public const string ImagesKey = "images";
 
         /// <remarks>string</remarks>
@@ -74,6 +76,7 @@ namespace SabreTools.Models.Internal
 
         /// TODO: This needs an internal model OR mapping to fields
         /// <remarks>Infos</remarks>
+        [NoFilter]
         public const string InfosKey = "infos";
 
         /// <remarks>(yes|no) "no"</remarks>
@@ -93,6 +96,7 @@ namespace SabreTools.Models.Internal
 
         /// TODO: This needs an internal model OR mapping to fields
         /// <remarks>NewDat</remarks>
+        [NoFilter]
         public const string NewDatKey = "newDat";
 
         /// <remarks>string</remarks>
@@ -127,6 +131,7 @@ namespace SabreTools.Models.Internal
 
         /// TODO: This needs an internal model OR mapping to fields
         /// <remarks>Search</remarks>
+        [NoFilter]
         public const string SearchKey = "search";
 
         /// <remarks>string</remarks>
diff --git a/SabreTools.Models/Internal/Machine.cs b/SabreTools.Models/Internal/Machine.cs
index 95dd5d0b..35f23d1e 100644
--- a/SabreTools.Models/Internal/Machine.cs
+++ b/SabreTools.Models/Internal/Machine.cs
@@ -8,12 +8,15 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Adjuster[]</remarks>
+        [NoFilter]
         public const string AdjusterKey = "adjuster";
 
         /// <remarks>Archive[]</remarks>
+        [NoFilter]
         public const string ArchiveKey = "archive";
 
         /// <remarks>BiosSet[]</remarks>
+        [NoFilter]
         public const string BiosSetKey = "biosset";
 
         /// <remarks>string</remarks>
@@ -26,6 +29,7 @@ namespace SabreTools.Models.Internal
         public const string CategoryKey = "category";
 
         /// <remarks>Chip[]</remarks>
+        [NoFilter]
         public const string ChipKey = "chip";
 
         /// <remarks>string</remarks>
@@ -41,6 +45,7 @@ namespace SabreTools.Models.Internal
         public const string CompanyKey = "company";
 
         /// <remarks>Configuration[]</remarks>
+        [NoFilter]
         public const string ConfigurationKey = "configuration";
 
         /// <remarks>string</remarks>
@@ -53,33 +58,40 @@ namespace SabreTools.Models.Internal
         public const string DescriptionKey = "description";
 
         /// <remarks>Device[]</remarks>
+        [NoFilter]
         public const string DeviceKey = "device";
 
         /// <remarks>DeviceRef[]</remarks>
+        [NoFilter]
         public const string DeviceRefKey = "device_ref";
 
         /// <remarks>DipSwitch[]</remarks>
+        [NoFilter]
         public const string DipSwitchKey = "dipswitch";
 
         /// <remarks>string</remarks>
         public const string DirNameKey = "dirName";
 
         /// <remarks>Disk[]</remarks>
+        [NoFilter]
         public const string DiskKey = "disk";
 
         /// <remarks>string</remarks>
         public const string DisplayCountKey = "displaycount";
 
         /// <remarks>Display[]</remarks>
+        [NoFilter]
         public const string DisplayKey = "display";
 
         /// <remarks>string</remarks>
         public const string DisplayTypeKey = "displaytype";
 
         /// <remarks>Driver</remarks>
+        [NoFilter]
         public const string DriverKey = "driver";
 
         /// <remarks>Dump[]</remarks>
+        [NoFilter]
         public const string DumpKey = "dump";
 
         /// <remarks>string</remarks>
@@ -95,6 +107,7 @@ namespace SabreTools.Models.Internal
         public const string FavoriteKey = "favorite";
 
         /// <remarks>Feature[]</remarks>
+        [NoFilter]
         public const string FeatureKey = "feature";
 
         /// <remarks>string</remarks>
@@ -116,9 +129,11 @@ namespace SabreTools.Models.Internal
         public const string ImageNumberKey = "imageNumber";
 
         /// <remarks>Info[]</remarks>
+        [NoFilter]
         public const string InfoKey = "info";
 
         /// <remarks>Input</remarks>
+        [NoFilter]
         public const string InputKey = "input";
 
         /// <remarks>(yes|no) "no"</remarks>
@@ -140,6 +155,7 @@ namespace SabreTools.Models.Internal
         public const string ManufacturerKey = "manufacturer";
 
         /// <remarks>Media[]</remarks>
+        [NoFilter]
         public const string MediaKey = "media";
 
         /// <remarks>string</remarks>
@@ -149,6 +165,7 @@ namespace SabreTools.Models.Internal
         public const string NotesKey = "notes";
 
         /// <remarks>Part[]</remarks>
+        [NoFilter]
         public const string PartKey = "part";
 
         /// <remarks>string</remarks>
@@ -161,24 +178,28 @@ namespace SabreTools.Models.Internal
         public const string PlayersKey = "players";
 
         /// <remarks>Port[]</remarks>
+        [NoFilter]
         public const string PortKey = "port";
 
         /// <remarks>string</remarks>
         public const string PublisherKey = "publisher";
 
         /// <remarks>RamOption[]</remarks>
+        [NoFilter]
         public const string RamOptionKey = "ramoption";
 
         /// <remarks>string</remarks>
         public const string RebuildToKey = "rebuildto";
 
         /// <remarks>Release[]</remarks>
+        [NoFilter]
         public const string ReleaseKey = "release";
 
         /// <remarks>string</remarks>
         public const string ReleaseNumberKey = "releaseNumber";
 
         /// <remarks>Rom[]</remarks>
+        [NoFilter]
         public const string RomKey = "rom";
 
         /// <remarks>string</remarks>
@@ -191,6 +212,7 @@ namespace SabreTools.Models.Internal
         public const string RunnableKey = "runnable";
 
         /// <remarks>Sample[]</remarks>
+        [NoFilter]
         public const string SampleKey = "sample";
 
         /// <remarks>string</remarks>
@@ -200,15 +222,19 @@ namespace SabreTools.Models.Internal
         public const string SaveTypeKey = "saveType";
 
         /// <remarks>SharedFeat[]</remarks>
+        [NoFilter]
         public const string SharedFeatKey = "sharedfeat";
 
         /// <remarks>Slot[]</remarks>
+        [NoFilter]
         public const string SlotKey = "slot";
 
         /// <remarks>SoftwareList[]</remarks>
+        [NoFilter]
         public const string SoftwareListKey = "softwarelist";
 
         /// <remarks>Sound</remarks>
+        [NoFilter]
         public const string SoundKey = "sound";
 
         /// <remarks>string</remarks>
@@ -231,9 +257,11 @@ namespace SabreTools.Models.Internal
 
         /// TODO: This needs an internal model OR mapping to fields
         /// <remarks>Trurip</remarks>
+        [NoFilter]
         public const string TruripKey = "trurip";
 
         /// <remarks>Video[]</remarks>
+        [NoFilter]
         public const string VideoKey = "video";
 
         /// <remarks>string</remarks>
diff --git a/SabreTools.Models/Internal/MetadataFile.cs b/SabreTools.Models/Internal/MetadataFile.cs
index 856ad3bf..0b1f5fc0 100644
--- a/SabreTools.Models/Internal/MetadataFile.cs
+++ b/SabreTools.Models/Internal/MetadataFile.cs
@@ -8,9 +8,11 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Machine[]</remarks>
+        [NoFilter]
         public const string MachineKey = "machine";
 
         /// <remarks>Header</remarks>
+        [NoFilter]
         public const string HeaderKey = "header";
 
         #endregion
diff --git a/SabreTools.Models/Internal/Part.cs b/SabreTools.Models/Internal/Part.cs
index cb9f7279..461623d3 100644
--- a/SabreTools.Models/Internal/Part.cs
+++ b/SabreTools.Models/Internal/Part.cs
@@ -9,15 +9,19 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>DataArea[]</remarks>
+        [NoFilter]
         public const string DataAreaKey = "dataarea";
 
         /// <remarks>DiskArea[]</remarks>
+        [NoFilter]
         public const string DiskAreaKey = "diskarea";
 
         /// <remarks>DipSwitch[]</remarks>
+        [NoFilter]
         public const string DipSwitchKey = "dipswitch";
 
         /// <remarks>Feature[]</remarks>
+        [NoFilter]
         public const string FeatureKey = "feature";
 
         /// <remarks>string</remarks>
diff --git a/SabreTools.Models/Internal/Port.cs b/SabreTools.Models/Internal/Port.cs
index 2e9275e5..231168c6 100644
--- a/SabreTools.Models/Internal/Port.cs
+++ b/SabreTools.Models/Internal/Port.cs
@@ -9,6 +9,7 @@ namespace SabreTools.Models.Internal
         #region Keys
 
         /// <remarks>Analog[]</remarks>
+        [NoFilter]
         public const string AnalogKey = "analog";
 
         /// <remarks>string</remarks>
diff --git a/SabreTools.Models/Internal/Slot.cs b/SabreTools.Models/Internal/Slot.cs
index 45325a8e..b40abc74 100644
--- a/SabreTools.Models/Internal/Slot.cs
+++ b/SabreTools.Models/Internal/Slot.cs
@@ -12,6 +12,7 @@ namespace SabreTools.Models.Internal
         public const string NameKey = "name";
 
         /// <remarks>SlotOption[]</remarks>
+        [NoFilter]
         public const string SlotOptionKey = "slotoption";
 
         #endregion
diff --git a/SabreTools.Models/Internal/Software.cs b/SabreTools.Models/Internal/Software.cs
index ba545b41..45e712e9 100644
--- a/SabreTools.Models/Internal/Software.cs
+++ b/SabreTools.Models/Internal/Software.cs
@@ -15,6 +15,7 @@ namespace SabreTools.Models.Internal
         public const string DescriptionKey = "description";
 
         /// <remarks>Info[]</remarks>
+        [NoFilter]
         public const string InfoKey = "info";
 
         /// <remarks>string</remarks>
@@ -24,12 +25,14 @@ namespace SabreTools.Models.Internal
         public const string NotesKey = "notes";
 
         /// <remarks>Part[]</remarks>
+        [NoFilter]
         public const string PartKey = "part";
 
         /// <remarks>string</remarks>
         public const string PublisherKey = "publisher";
 
         /// <remarks>SharedFeat[]</remarks>
+        [NoFilter]
         public const string SharedFeatKey = "sharedfeat";
 
         /// <remarks>(yes|partial|no) "yes"</remarks>
diff --git a/SabreTools.Models/Internal/SoftwareList.cs b/SabreTools.Models/Internal/SoftwareList.cs
index 100fb71e..d7666659 100644
--- a/SabreTools.Models/Internal/SoftwareList.cs
+++ b/SabreTools.Models/Internal/SoftwareList.cs
@@ -21,6 +21,7 @@ namespace SabreTools.Models.Internal
         public const string NotesKey = "notes";
 
         /// <remarks>Software[]</remarks>
+        [NoFilter]
         public const string SoftwareKey = "software";
 
         /// <remarks>(original|compatible)</remarks>
diff --git a/SabreTools.Models/NoFilterAttribute.cs b/SabreTools.Models/NoFilterAttribute.cs
new file mode 100644
index 00000000..314be39b
--- /dev/null
+++ b/SabreTools.Models/NoFilterAttribute.cs
@@ -0,0 +1,8 @@
+namespace SabreTools.Models
+{
+    /// <summary>
+    /// Marks a property as required on write
+    /// </summary>
+    [System.AttributeUsage(System.AttributeTargets.Field)]
+    public class NoFilterAttribute : System.Attribute { }
+}
\ No newline at end of file