diff --git a/SabreTools.Models/AttractMode/MetadataFile.cs b/SabreTools.Models/AttractMode/MetadataFile.cs
index ec72fac2..b1b78a0d 100644
--- a/SabreTools.Models/AttractMode/MetadataFile.cs
+++ b/SabreTools.Models/AttractMode/MetadataFile.cs
@@ -5,7 +5,8 @@ namespace SabreTools.Models.AttractMode
     /// </summary>
     public class MetadataFile
     {
-        public string[] Header { get; set; }
+        [Required]
+        public string[]? Header { get; set; }
 
         public Row[]? Row { get; set; }
     }
diff --git a/SabreTools.Models/AttractMode/Row.cs b/SabreTools.Models/AttractMode/Row.cs
index bf8d300e..17fc57f3 100644
--- a/SabreTools.Models/AttractMode/Row.cs
+++ b/SabreTools.Models/AttractMode/Row.cs
@@ -3,7 +3,8 @@ namespace SabreTools.Models.AttractMode
     public class Row
     {
         /// <remarks>Also called Romname</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         public string? Title { get; set; }
 
diff --git a/SabreTools.Models/ClrMamePro/Archive.cs b/SabreTools.Models/ClrMamePro/Archive.cs
index 498c7183..2cd03795 100644
--- a/SabreTools.Models/ClrMamePro/Archive.cs
+++ b/SabreTools.Models/ClrMamePro/Archive.cs
@@ -4,7 +4,8 @@ namespace SabreTools.Models.ClrMamePro
     public class Archive
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/ClrMamePro/BiosSet.cs b/SabreTools.Models/ClrMamePro/BiosSet.cs
index fe1dfa86..54326691 100644
--- a/SabreTools.Models/ClrMamePro/BiosSet.cs
+++ b/SabreTools.Models/ClrMamePro/BiosSet.cs
@@ -4,10 +4,12 @@ namespace SabreTools.Models.ClrMamePro
     public class BiosSet
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>description</remarks>
-        public string Description { get; set; }
+        [Required]
+        public string? Description { get; set; }
 
         /// <remarks>default</remarks>
         public string? Default { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/Chip.cs b/SabreTools.Models/ClrMamePro/Chip.cs
index f7d3a299..d542d568 100644
--- a/SabreTools.Models/ClrMamePro/Chip.cs
+++ b/SabreTools.Models/ClrMamePro/Chip.cs
@@ -4,10 +4,12 @@ namespace SabreTools.Models.ClrMamePro
     public class Chip
     {
         /// <remarks>type, (cpu|audio)</remarks>
-        public string Type { get; set; }
+        [Required]
+        public string? Type { get; set; }
 
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>flags</remarks>
         public string? Flags { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/DipSwitch.cs b/SabreTools.Models/ClrMamePro/DipSwitch.cs
index 46c5f09e..38708414 100644
--- a/SabreTools.Models/ClrMamePro/DipSwitch.cs
+++ b/SabreTools.Models/ClrMamePro/DipSwitch.cs
@@ -4,7 +4,8 @@ namespace SabreTools.Models.ClrMamePro
     public class DipSwitch
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>entry</remarks>
         public string[]? Entry { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/Disk.cs b/SabreTools.Models/ClrMamePro/Disk.cs
index 23407c37..0a84fa3f 100644
--- a/SabreTools.Models/ClrMamePro/Disk.cs
+++ b/SabreTools.Models/ClrMamePro/Disk.cs
@@ -4,7 +4,8 @@ namespace SabreTools.Models.ClrMamePro
     public class Disk
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>md5</remarks>
         public string? MD5 { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/Driver.cs b/SabreTools.Models/ClrMamePro/Driver.cs
index f84b3a78..f1656e57 100644
--- a/SabreTools.Models/ClrMamePro/Driver.cs
+++ b/SabreTools.Models/ClrMamePro/Driver.cs
@@ -4,7 +4,8 @@ namespace SabreTools.Models.ClrMamePro
     public class Driver
     {
         /// <remarks>status, (good|imperfect|preliminary)</remarks>
-        public string Status { get; set; }
+        [Required]
+        public string? Status { get; set; }
 
         /// <remarks>color, (good|imperfect|preliminary)</remarks>
         public string? Color { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/GameBase.cs b/SabreTools.Models/ClrMamePro/GameBase.cs
index 1efbd9fb..ca234095 100644
--- a/SabreTools.Models/ClrMamePro/GameBase.cs
+++ b/SabreTools.Models/ClrMamePro/GameBase.cs
@@ -6,7 +6,8 @@ namespace SabreTools.Models.ClrMamePro
     public abstract class GameBase
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>description</remarks>
         public string? Description { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/Input.cs b/SabreTools.Models/ClrMamePro/Input.cs
index 76c416bc..06da37b2 100644
--- a/SabreTools.Models/ClrMamePro/Input.cs
+++ b/SabreTools.Models/ClrMamePro/Input.cs
@@ -3,14 +3,16 @@ namespace SabreTools.Models.ClrMamePro
     /// <remarks>input</remarks>
     public class Input
     {
-        /// <remarks>players, Numeric?/remarks>
-        public string Players { get; set; }
+        /// <remarks>players, Numeric/remarks>
+        [Required]
+        public string? Players { get; set; }
 
         /// <remarks>control</remarks>
         public string? Control { get; set; }
 
         /// <remarks>buttons, Numeric</remarks>
-        public string Buttons { get; set; }
+        [Required]
+        public string? Buttons { get; set; }
 
         /// <remarks>coins, Numeric</remarks>
         public string? Coins { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/Media.cs b/SabreTools.Models/ClrMamePro/Media.cs
index 9a8d66d4..25f678aa 100644
--- a/SabreTools.Models/ClrMamePro/Media.cs
+++ b/SabreTools.Models/ClrMamePro/Media.cs
@@ -4,7 +4,8 @@ namespace SabreTools.Models.ClrMamePro
     public class Media
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>md5</remarks>
         public string? MD5 { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/Release.cs b/SabreTools.Models/ClrMamePro/Release.cs
index 69f73c20..1da26ca3 100644
--- a/SabreTools.Models/ClrMamePro/Release.cs
+++ b/SabreTools.Models/ClrMamePro/Release.cs
@@ -4,10 +4,12 @@ namespace SabreTools.Models.ClrMamePro
     public class Release
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>region</remarks>
-        public string Region { get; set; }
+        [Required]
+        public string? Region { get; set; }
 
         /// <remarks>language</remarks>
         public string? Language { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/Rom.cs b/SabreTools.Models/ClrMamePro/Rom.cs
index 250da8c2..a98677ed 100644
--- a/SabreTools.Models/ClrMamePro/Rom.cs
+++ b/SabreTools.Models/ClrMamePro/Rom.cs
@@ -4,10 +4,12 @@ namespace SabreTools.Models.ClrMamePro
     public class Rom
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>size, Numeric</remarks>
-        public string Size { get; set; }
+        [Required]
+        public string? Size { get; set; }
 
         /// <remarks>crc</remarks>
         public string? CRC { get; set; }
diff --git a/SabreTools.Models/ClrMamePro/Sample.cs b/SabreTools.Models/ClrMamePro/Sample.cs
index bfada9d7..ab0b11c1 100644
--- a/SabreTools.Models/ClrMamePro/Sample.cs
+++ b/SabreTools.Models/ClrMamePro/Sample.cs
@@ -4,7 +4,8 @@ namespace SabreTools.Models.ClrMamePro
     public class Sample
     {
         /// <remarks>name</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/ClrMamePro/Sound.cs b/SabreTools.Models/ClrMamePro/Sound.cs
index 3c37f621..bfddee8b 100644
--- a/SabreTools.Models/ClrMamePro/Sound.cs
+++ b/SabreTools.Models/ClrMamePro/Sound.cs
@@ -4,7 +4,8 @@ namespace SabreTools.Models.ClrMamePro
     public class Sound
     {
         /// <remarks>channels, Numeric?</remarks>
-        public string Channels { get; set; }
+        [Required]
+        public string? Channels { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/ClrMamePro/Video.cs b/SabreTools.Models/ClrMamePro/Video.cs
index d946bade..c7448aa8 100644
--- a/SabreTools.Models/ClrMamePro/Video.cs
+++ b/SabreTools.Models/ClrMamePro/Video.cs
@@ -4,10 +4,12 @@ namespace SabreTools.Models.ClrMamePro
     public class Video
     {
         /// <remarks>screen, (raster|vector)</remarks>
-        public string Screen { get; set; }
+        [Required]
+        public string? Screen { get; set; }
 
         /// <remarks>orientation, (vertical|horizontal)</remarks>
-        public string Orientation { get; set; }
+        [Required]
+        public string? Orientation { get; set; }
 
         /// <remarks>x, Numeric?</remarks>
         public string? X { get; set; }
diff --git a/SabreTools.Models/DosCenter/File.cs b/SabreTools.Models/DosCenter/File.cs
index 1ae126c1..eb663f45 100644
--- a/SabreTools.Models/DosCenter/File.cs
+++ b/SabreTools.Models/DosCenter/File.cs
@@ -4,13 +4,16 @@ namespace SabreTools.Models.DosCenter
     public class File
     {
         /// <remarks>name, attribute</remarks>
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         /// <remarks>size, attribute, numeric</remarks>
-        public string Size { get; set; }
+        [Required]
+        public string? Size { get; set; }
 
         /// <remarks>crc, attribute</remarks>
-        public string CRC { get; set; }
+        [Required]
+        public string? CRC { get; set; }
 
         /// <remarks>date, attribute</remarks>
         public string? Date { get; set; }
diff --git a/SabreTools.Models/DosCenter/Game.cs b/SabreTools.Models/DosCenter/Game.cs
index 3f5b159a..8413155c 100644
--- a/SabreTools.Models/DosCenter/Game.cs
+++ b/SabreTools.Models/DosCenter/Game.cs
@@ -4,6 +4,7 @@ namespace SabreTools.Models.DosCenter
     public class Game
     {
         /// <remarks>name</remarks>
+        [Required]
         public string? Name { get; set; }
 
         /// <remarks>file</remarks>
diff --git a/SabreTools.Models/EverdriveSMDB/Row.cs b/SabreTools.Models/EverdriveSMDB/Row.cs
index fd89b184..648dbe4d 100644
--- a/SabreTools.Models/EverdriveSMDB/Row.cs
+++ b/SabreTools.Models/EverdriveSMDB/Row.cs
@@ -5,15 +5,20 @@ namespace SabreTools.Models.EverdriveSMDB
     /// </summary>
     public class Row
     {
-        public string SHA256 { get; set; }
+        [Required]
+        public string? SHA256 { get; set; }
 
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
-        public string SHA1 { get; set; }
+        [Required]
+        public string? SHA1 { get; set; }
 
-        public string MD5 { get; set; }
+        [Required]
+        public string? MD5 { get; set; }
 
-        public string CRC32 { get; set; }
+        [Required]
+        public string? CRC32 { get; set; }
 
         public string? Size { get; set; }
 
diff --git a/SabreTools.Models/Hashfile/MD5.cs b/SabreTools.Models/Hashfile/MD5.cs
index 45a8fa83..1156d18a 100644
--- a/SabreTools.Models/Hashfile/MD5.cs
+++ b/SabreTools.Models/Hashfile/MD5.cs
@@ -5,8 +5,10 @@ namespace SabreTools.Models.Hashfile
     /// </summary>
     public class MD5
     {
-        public string Hash { get; set; }
+        [Required]
+        public string? Hash { get; set; }
 
-        public string File { get; set; }
+        [Required]
+        public string? File { get; set; }
     }
 }
\ No newline at end of file
diff --git a/SabreTools.Models/Hashfile/SFV.cs b/SabreTools.Models/Hashfile/SFV.cs
index 50ec621e..8d4be7f2 100644
--- a/SabreTools.Models/Hashfile/SFV.cs
+++ b/SabreTools.Models/Hashfile/SFV.cs
@@ -5,8 +5,10 @@ namespace SabreTools.Models.Hashfile
     /// </summary>
     public class SFV
     {
-        public string File { get; set; }
+        [Required]
+        public string? File { get; set; }
 
-        public string Hash { get; set; }
+        [Required]
+        public string? Hash { get; set; }
     }
 }
\ No newline at end of file
diff --git a/SabreTools.Models/Hashfile/SHA1.cs b/SabreTools.Models/Hashfile/SHA1.cs
index df7008a7..153afb3e 100644
--- a/SabreTools.Models/Hashfile/SHA1.cs
+++ b/SabreTools.Models/Hashfile/SHA1.cs
@@ -5,8 +5,10 @@ namespace SabreTools.Models.Hashfile
     /// </summary>
     public class SHA1
     {
-        public string Hash { get; set; }
+        [Required]
+        public string? Hash { get; set; }
 
-        public string File { get; set; }
+        [Required]
+        public string? File { get; set; }
     }
 }
\ No newline at end of file
diff --git a/SabreTools.Models/Hashfile/SHA256.cs b/SabreTools.Models/Hashfile/SHA256.cs
index 1761443b..9b2c6d2a 100644
--- a/SabreTools.Models/Hashfile/SHA256.cs
+++ b/SabreTools.Models/Hashfile/SHA256.cs
@@ -5,8 +5,10 @@ namespace SabreTools.Models.Hashfile
     /// </summary>
     public class SHA256
     {
-        public string Hash { get; set; }
+        [Required]
+        public string? Hash { get; set; }
 
-        public string File { get; set; }
+        [Required]
+        public string? File { get; set; }
     }
 }
\ No newline at end of file
diff --git a/SabreTools.Models/Hashfile/SHA384.cs b/SabreTools.Models/Hashfile/SHA384.cs
index ab393ecf..916aa710 100644
--- a/SabreTools.Models/Hashfile/SHA384.cs
+++ b/SabreTools.Models/Hashfile/SHA384.cs
@@ -5,8 +5,10 @@ namespace SabreTools.Models.Hashfile
     /// </summary>
     public class SHA384
     {
-        public string Hash { get; set; }
+        [Required]
+        public string? Hash { get; set; }
 
-        public string File { get; set; }
+        [Required]
+        public string? File { get; set; }
     }
 }
\ No newline at end of file
diff --git a/SabreTools.Models/Hashfile/SHA512.cs b/SabreTools.Models/Hashfile/SHA512.cs
index bcd2055c..dec6abb7 100644
--- a/SabreTools.Models/Hashfile/SHA512.cs
+++ b/SabreTools.Models/Hashfile/SHA512.cs
@@ -5,8 +5,10 @@ namespace SabreTools.Models.Hashfile
     /// </summary>
     public class SHA512
     {
-        public string Hash { get; set; }
+        [Required]
+        public string? Hash { get; set; }
 
-        public string File { get; set; }
+        [Required]
+        public string? File { get; set; }
     }
 }
\ No newline at end of file
diff --git a/SabreTools.Models/Hashfile/SpamSum.cs b/SabreTools.Models/Hashfile/SpamSum.cs
index c3a9363e..82bb61ea 100644
--- a/SabreTools.Models/Hashfile/SpamSum.cs
+++ b/SabreTools.Models/Hashfile/SpamSum.cs
@@ -5,8 +5,10 @@ namespace SabreTools.Models.Hashfile
     /// </summary>
     public class SpamSum
     {
-        public string Hash { get; set; }
+        [Required]
+        public string? Hash { get; set; }
 
-        public string File { get; set; }
+        [Required]
+        public string? File { get; set; }
     }
 }
\ No newline at end of file
diff --git a/SabreTools.Models/Listrom/Row.cs b/SabreTools.Models/Listrom/Row.cs
index f6a62f1a..4f3dce97 100644
--- a/SabreTools.Models/Listrom/Row.cs
+++ b/SabreTools.Models/Listrom/Row.cs
@@ -14,7 +14,8 @@ namespace SabreTools.Models.Listrom
     /// </summary>
     public class Row
     {
-        public string Name { get; set; }
+        [Required]
+        public string? Name { get; set; }
 
         public string? Size { get; set; }
 
diff --git a/SabreTools.Models/Listxml/Adjuster.cs b/SabreTools.Models/Listxml/Adjuster.cs
index 37970024..f5d6de1a 100644
--- a/SabreTools.Models/Listxml/Adjuster.cs
+++ b/SabreTools.Models/Listxml/Adjuster.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("adjuster")]
     public class Adjuster
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("default")]
diff --git a/SabreTools.Models/Listxml/Analog.cs b/SabreTools.Models/Listxml/Analog.cs
index 8f4a1baf..1effbaf5 100644
--- a/SabreTools.Models/Listxml/Analog.cs
+++ b/SabreTools.Models/Listxml/Analog.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("analog")]
     public class Analog
     {
+        [Required]
         [XmlAttribute("mask")]
-        public string Mask { get; set; }
+        public string? Mask { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/BiosSet.cs b/SabreTools.Models/Listxml/BiosSet.cs
index 2399b4d3..51dc9e3d 100644
--- a/SabreTools.Models/Listxml/BiosSet.cs
+++ b/SabreTools.Models/Listxml/BiosSet.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("biosset")]
     public class BiosSet
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("description")]
-        public string Description { get; set; }
+        public string? Description { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("default")]
diff --git a/SabreTools.Models/Listxml/Chip.cs b/SabreTools.Models/Listxml/Chip.cs
index 56cf0ee6..dc722b83 100644
--- a/SabreTools.Models/Listxml/Chip.cs
+++ b/SabreTools.Models/Listxml/Chip.cs
@@ -6,15 +6,17 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("chip")]
     public class Chip
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("tag")]
         public string? Tag { get; set; }
 
         /// <remarks>(cpu|audio)</remarks>
+        [Required]
         [XmlAttribute("type")]
-        public string Type { get; set; }
+        public string? Type { get; set; }
 
         /// <remarks>Only present in older versions</remarks>
         [XmlAttribute("soundonly")]
diff --git a/SabreTools.Models/Listxml/Condition.cs b/SabreTools.Models/Listxml/Condition.cs
index 8746d61b..ddf02c66 100644
--- a/SabreTools.Models/Listxml/Condition.cs
+++ b/SabreTools.Models/Listxml/Condition.cs
@@ -6,18 +6,22 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("condition")]
     public class Condition
     {
+        [Required]
         [XmlAttribute("tag")]
-        public string Tag { get; set; }
+        public string? Tag { get; set; }
 
+        [Required]
         [XmlAttribute("mask")]
-        public string Mask { get; set; }
+        public string? Mask { get; set; }
 
         /// <remarks>(eq|ne|gt|le|lt|ge)</remarks>
+        [Required]
         [XmlAttribute("relation")]
-        public string Relation { get; set; }
+        public string? Relation { get; set; }
 
+        [Required]
         [XmlAttribute("value")]
-        public string Value { get; set; }
+        public string? Value { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/ConfLocation.cs b/SabreTools.Models/Listxml/ConfLocation.cs
index 087504b5..9199c715 100644
--- a/SabreTools.Models/Listxml/ConfLocation.cs
+++ b/SabreTools.Models/Listxml/ConfLocation.cs
@@ -6,12 +6,14 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("conflocation")]
     public class ConfLocation
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         /// <remarks>Numeric?</remarks>
+        [Required]
         [XmlAttribute("number")]
-        public string Number { get; set; }
+        public string? Number { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("inverted")]
diff --git a/SabreTools.Models/Listxml/ConfSetting.cs b/SabreTools.Models/Listxml/ConfSetting.cs
index 7a58348b..2d3d972d 100644
--- a/SabreTools.Models/Listxml/ConfSetting.cs
+++ b/SabreTools.Models/Listxml/ConfSetting.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("confsetting")]
     public class ConfSetting
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("value")]
-        public string Value { get; set; }
+        public string? Value { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("default")]
diff --git a/SabreTools.Models/Listxml/Configuration.cs b/SabreTools.Models/Listxml/Configuration.cs
index faeb7b1e..1871ad70 100644
--- a/SabreTools.Models/Listxml/Configuration.cs
+++ b/SabreTools.Models/Listxml/Configuration.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("configuration")]
     public class Configuration
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("tag")]
-        public string Tag { get; set; }
+        public string? Tag { get; set; }
 
         [XmlAttribute("mask")]
         public string? Mask { get; set; }
diff --git a/SabreTools.Models/Listxml/Control.cs b/SabreTools.Models/Listxml/Control.cs
index 86032b3a..c517de7c 100644
--- a/SabreTools.Models/Listxml/Control.cs
+++ b/SabreTools.Models/Listxml/Control.cs
@@ -7,8 +7,9 @@ namespace SabreTools.Models.Listxml
     public class Control
     {
         /// <remarks>(joy|stick|paddle|pedal|lightgun|positional|dial|trackball|mouse|only_buttons|keypad|keyboard|mahjong|hanafuda|gambling)</remarks>
+        [Required]
         [XmlAttribute("type")]
-        public string Type { get; set; }
+        public string? Type { get; set; }
 
         /// <remarks>Numeric</remarks>
         [XmlAttribute("player")]
diff --git a/SabreTools.Models/Listxml/Device.cs b/SabreTools.Models/Listxml/Device.cs
index 139d8d36..ceb17d66 100644
--- a/SabreTools.Models/Listxml/Device.cs
+++ b/SabreTools.Models/Listxml/Device.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("device")]
     public class Device
     {
+        [Required]
         [XmlAttribute("type")]
-        public string Type { get; set; }
+        public string? Type { get; set; }
 
         [XmlAttribute("tag")]
         public string? Tag { get; set; }
diff --git a/SabreTools.Models/Listxml/DeviceRef.cs b/SabreTools.Models/Listxml/DeviceRef.cs
index b43639b9..f9b5d8c6 100644
--- a/SabreTools.Models/Listxml/DeviceRef.cs
+++ b/SabreTools.Models/Listxml/DeviceRef.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("device_ref")]
     public class DeviceRef
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/DipLocation.cs b/SabreTools.Models/Listxml/DipLocation.cs
index dbdd4b10..adb628d3 100644
--- a/SabreTools.Models/Listxml/DipLocation.cs
+++ b/SabreTools.Models/Listxml/DipLocation.cs
@@ -6,12 +6,14 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("diplocation")]
     public class DipLocation
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         /// <remarks>Numeric?</remarks>
+        [Required]
         [XmlAttribute("number")]
-        public string Number { get; set; }
+        public string? Number { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("inverted")]
diff --git a/SabreTools.Models/Listxml/DipSwitch.cs b/SabreTools.Models/Listxml/DipSwitch.cs
index 1754258f..13ab0d96 100644
--- a/SabreTools.Models/Listxml/DipSwitch.cs
+++ b/SabreTools.Models/Listxml/DipSwitch.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("dipswitch")]
     public class DipSwitch
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("tag")]
-        public string Tag { get; set; }
+        public string? Tag { get; set; }
 
         [XmlAttribute("mask")]
         public string? Mask { get; set; }
diff --git a/SabreTools.Models/Listxml/DipValue.cs b/SabreTools.Models/Listxml/DipValue.cs
index fd6d8ce8..e48a9838 100644
--- a/SabreTools.Models/Listxml/DipValue.cs
+++ b/SabreTools.Models/Listxml/DipValue.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("dipvalue")]
     public class DipValue
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("value")]
-        public string Value { get; set; }
+        public string? Value { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("default")]
diff --git a/SabreTools.Models/Listxml/Disk.cs b/SabreTools.Models/Listxml/Disk.cs
index 5807ce5f..bd979a9b 100644
--- a/SabreTools.Models/Listxml/Disk.cs
+++ b/SabreTools.Models/Listxml/Disk.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("disk")]
     public class Disk
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         /// <remarks>Only present in older versions</remarks>
         [XmlAttribute("md5")]
diff --git a/SabreTools.Models/Listxml/Display.cs b/SabreTools.Models/Listxml/Display.cs
index 0a4bed41..1763d7fe 100644
--- a/SabreTools.Models/Listxml/Display.cs
+++ b/SabreTools.Models/Listxml/Display.cs
@@ -10,8 +10,9 @@ namespace SabreTools.Models.Listxml
         public string? Tag { get; set; }
 
         /// <remarks>(raster|vector|lcd|svg|unknown)</remarks>
+        [Required]
         [XmlAttribute("type")]
-        public string Type { get; set; }
+        public string? Type { get; set; }
 
         /// <remarks>(0|90|180|270)</remarks>
         [XmlAttribute("rotate")]
@@ -30,8 +31,9 @@ namespace SabreTools.Models.Listxml
         public string? Height { get; set; }
 
         /// <remarks>Numeric</remarks>
+        [Required]
         [XmlAttribute("refresh")]
-        public string Refresh { get; set; }
+        public string? Refresh { get; set; }
 
         /// <remarks>Numeric</remarks>
         [XmlAttribute("pixclock")]
diff --git a/SabreTools.Models/Listxml/Driver.cs b/SabreTools.Models/Listxml/Driver.cs
index 23ca06fe..e4480017 100644
--- a/SabreTools.Models/Listxml/Driver.cs
+++ b/SabreTools.Models/Listxml/Driver.cs
@@ -7,8 +7,9 @@ namespace SabreTools.Models.Listxml
     public class Driver
     {
         /// <remarks>(good|imperfect|preliminary), (good|preliminary|test) in older versions</remarks>
+        [Required]
         [XmlAttribute("status")]
-        public string Status { get; set; }
+        public string? Status { get; set; }
 
         /// <remarks>(good|imperfect|preliminary), Only present in older versions</remarks>
         [XmlAttribute("color")]
@@ -23,16 +24,19 @@ namespace SabreTools.Models.Listxml
         public string? PaletteSize { get; set; }
 
         /// <remarks>(good|imperfect|preliminary)</remarks>
+        [Required]
         [XmlAttribute("emulation")]
-        public string Emulation { get; set; }
+        public string? Emulation { get; set; }
 
         /// <remarks>(good|imperfect|preliminary)</remarks>
+        [Required]
         [XmlAttribute("cocktail")]
-        public string Cocktail { get; set; }
+        public string? Cocktail { get; set; }
 
         /// <remarks>(supported|unsupported)</remarks>
+        [Required]
         [XmlAttribute("savestate")]
-        public string SaveState { get; set; }
+        public string? SaveState { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("requiresartwork")]
diff --git a/SabreTools.Models/Listxml/Extension.cs b/SabreTools.Models/Listxml/Extension.cs
index 4647e333..a73f4909 100644
--- a/SabreTools.Models/Listxml/Extension.cs
+++ b/SabreTools.Models/Listxml/Extension.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("extension")]
     public class Extension
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/Feature.cs b/SabreTools.Models/Listxml/Feature.cs
index ac85d181..9610218a 100644
--- a/SabreTools.Models/Listxml/Feature.cs
+++ b/SabreTools.Models/Listxml/Feature.cs
@@ -7,8 +7,9 @@ namespace SabreTools.Models.Listxml
     public class Feature
     {
         /// <remarks>(protection|timing|graphics|palette|sound|capture|camera|microphone|controls|keyboard|mouse|media|disk|printer|tape|punch|drum|rom|comms|lan|wan)</remarks>
+        [Required]
         [XmlAttribute("type")]
-        public string Type { get; set; }
+        public string? Type { get; set; }
 
         /// <remarks>(unemulated|imperfect)</remarks>
         [XmlAttribute("status")]
diff --git a/SabreTools.Models/Listxml/GameBase.cs b/SabreTools.Models/Listxml/GameBase.cs
index 26507a91..cbb7444d 100644
--- a/SabreTools.Models/Listxml/GameBase.cs
+++ b/SabreTools.Models/Listxml/GameBase.cs
@@ -8,8 +8,9 @@ namespace SabreTools.Models.Listxml
     /// </summary>
     public abstract class GameBase
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         /// <remarks>Machine only</remarks>
         [XmlAttribute("sourcefile")]
@@ -40,8 +41,9 @@ namespace SabreTools.Models.Listxml
         [XmlAttribute("sampleof")]
         public string? SampleOf { get; set; }
 
+        [Required]
         [XmlElement("description")]
-        public string Description { get; set; }
+        public string? Description { get; set; }
 
         [XmlElement("year")]
         public string? Year { get; set; }
diff --git a/SabreTools.Models/Listxml/Input.cs b/SabreTools.Models/Listxml/Input.cs
index a16f9cb0..26a76c11 100644
--- a/SabreTools.Models/Listxml/Input.cs
+++ b/SabreTools.Models/Listxml/Input.cs
@@ -15,8 +15,9 @@ namespace SabreTools.Models.Listxml
         public string? Tilt { get; set; }
 
         /// <remarks>Numeric</remarks>
+        [Required]
         [XmlAttribute("players")]
-        public string Players { get; set; }
+        public string? Players { get; set; }
 
         /// <remarks>Only present in older versions</remarks>
         [XmlAttribute("control")]
diff --git a/SabreTools.Models/Listxml/Instance.cs b/SabreTools.Models/Listxml/Instance.cs
index 43d51238..9711a791 100644
--- a/SabreTools.Models/Listxml/Instance.cs
+++ b/SabreTools.Models/Listxml/Instance.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("instance")]
     public class Instance
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("briefname")]
-        public string BriefName { get; set; }
+        public string? BriefName { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/M1.cs b/SabreTools.Models/Listxml/M1.cs
index 977faa9d..a5529ad7 100644
--- a/SabreTools.Models/Listxml/M1.cs
+++ b/SabreTools.Models/Listxml/M1.cs
@@ -11,7 +11,7 @@ namespace SabreTools.Models.Listxml
 
         [XmlElement("machine", typeof(Machine))]
         [XmlElement("game", typeof(Game))]
-        public GameBase[] Game { get; set; }
+        public GameBase[]? Game { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/Mame.cs b/SabreTools.Models/Listxml/Mame.cs
index 6b03008e..00117be0 100644
--- a/SabreTools.Models/Listxml/Mame.cs
+++ b/SabreTools.Models/Listxml/Mame.cs
@@ -13,12 +13,13 @@ namespace SabreTools.Models.Listxml
         [XmlAttribute("debug")]
         public string? Debug { get; set; }
 
+        [Required]
         [XmlAttribute("mameconfig")]
-        public string MameConfig { get; set; }
+        public string? MameConfig { get; set; }
 
         [XmlElement("machine", typeof(Machine))]
         [XmlElement("game", typeof(Game))]
-        public GameBase[] Game { get; set; }
+        public GameBase[]? Game { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/Port.cs b/SabreTools.Models/Listxml/Port.cs
index f647add3..fe4a6c65 100644
--- a/SabreTools.Models/Listxml/Port.cs
+++ b/SabreTools.Models/Listxml/Port.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("port")]
     public class Port
     {
+        [Required]
         [XmlAttribute("tag")]
-        public string Tag { get; set; }
+        public string? Tag { get; set; }
 
         [XmlElement("analog")]
         public Analog[]? Analog { get; set; }
diff --git a/SabreTools.Models/Listxml/RamOption.cs b/SabreTools.Models/Listxml/RamOption.cs
index 698944cd..f3e42f7c 100644
--- a/SabreTools.Models/Listxml/RamOption.cs
+++ b/SabreTools.Models/Listxml/RamOption.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("ramoption")]
     public class RamOption
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("default")]
         public string? Default { get; set; }
diff --git a/SabreTools.Models/Listxml/Rom.cs b/SabreTools.Models/Listxml/Rom.cs
index 6414e417..9f978fe9 100644
--- a/SabreTools.Models/Listxml/Rom.cs
+++ b/SabreTools.Models/Listxml/Rom.cs
@@ -6,15 +6,17 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("rom")]
     public class Rom
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("bios")]
         public string? Bios { get; set; }
 
         /// <remarks>Numeric</remarks>
+        [Required]
         [XmlAttribute("size")]
-        public string Size { get; set; }
+        public string? Size { get; set; }
 
         [XmlAttribute("crc")]
         public string? CRC { get; set; }
diff --git a/SabreTools.Models/Listxml/Sample.cs b/SabreTools.Models/Listxml/Sample.cs
index 05278a56..fdfd56bd 100644
--- a/SabreTools.Models/Listxml/Sample.cs
+++ b/SabreTools.Models/Listxml/Sample.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("sample")]
     public class Sample
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/Slot.cs b/SabreTools.Models/Listxml/Slot.cs
index cf662402..945194af 100644
--- a/SabreTools.Models/Listxml/Slot.cs
+++ b/SabreTools.Models/Listxml/Slot.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("slot")]
     public class Slot
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlElement("slotoption")]
         public SlotOption[]? SlotOption { get; set; }
diff --git a/SabreTools.Models/Listxml/SlotOption.cs b/SabreTools.Models/Listxml/SlotOption.cs
index 9e28c9dc..b47b8273 100644
--- a/SabreTools.Models/Listxml/SlotOption.cs
+++ b/SabreTools.Models/Listxml/SlotOption.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("slotoption")]
     public class SlotOption
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("devname")]
-        public string DevName { get; set; }
+        public string? DevName { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("default")]
diff --git a/SabreTools.Models/Listxml/SoftwareList.cs b/SabreTools.Models/Listxml/SoftwareList.cs
index de304959..7ae155b1 100644
--- a/SabreTools.Models/Listxml/SoftwareList.cs
+++ b/SabreTools.Models/Listxml/SoftwareList.cs
@@ -6,15 +6,18 @@ namespace SabreTools.Models.Listxml
     [XmlRoot("softwarelist")]
     public class SoftwareList
     {
+        [Required]
         [XmlAttribute("tag")]
-        public string Tag { get; set; }
+        public string? Tag { get; set; }
 
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         /// <remarks>(original|compatible)</remarks>
+        [Required]
         [XmlAttribute("status")]
-        public string Status { get; set; }
+        public string? Status { get; set; }
 
         [XmlAttribute("filter")]
         public string? Filter { get; set; }
diff --git a/SabreTools.Models/Listxml/Sound.cs b/SabreTools.Models/Listxml/Sound.cs
index 83f958c1..5b6c25d8 100644
--- a/SabreTools.Models/Listxml/Sound.cs
+++ b/SabreTools.Models/Listxml/Sound.cs
@@ -7,8 +7,9 @@ namespace SabreTools.Models.Listxml
     public class Sound
     {
         /// <remarks>Numeric</remarks>
+        [Required]
         [XmlAttribute("channels")]
-        public string Channels { get; set; }
+        public string? Channels { get; set; }
 
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Listxml/Video.cs b/SabreTools.Models/Listxml/Video.cs
index 0f035f05..f50d399f 100644
--- a/SabreTools.Models/Listxml/Video.cs
+++ b/SabreTools.Models/Listxml/Video.cs
@@ -7,12 +7,14 @@ namespace SabreTools.Models.Listxml
     public class Video
     {
         /// <remarks>(raster|vector)</remarks>
+        [Required]
         [XmlAttribute("screen")]
-        public string Screen { get; set; }
+        public string? Screen { get; set; }
 
         /// <remarks>(vertical|horizontal)</remarks>
+        [Required]
         [XmlAttribute("orientation")]
-        public string Orientation { get; set; }
+        public string? Orientation { get; set; }
 
         /// <remarks>Numeric</remarks>
         [XmlAttribute("width")]
diff --git a/SabreTools.Models/Logiqx/Archive.cs b/SabreTools.Models/Logiqx/Archive.cs
index 116e92b2..60889b0c 100644
--- a/SabreTools.Models/Logiqx/Archive.cs
+++ b/SabreTools.Models/Logiqx/Archive.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("archive")]
     public class Archive
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
         
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Logiqx/BiosSet.cs b/SabreTools.Models/Logiqx/BiosSet.cs
index 6ee7315c..2695739b 100644
--- a/SabreTools.Models/Logiqx/BiosSet.cs
+++ b/SabreTools.Models/Logiqx/BiosSet.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("biosset")]
     public class BiosSet
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("description")]
-        public string Description { get; set; }
+        public string? Description { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("default")]
diff --git a/SabreTools.Models/Logiqx/DeviceRef.cs b/SabreTools.Models/Logiqx/DeviceRef.cs
index bad6f97e..7d6ae1b6 100644
--- a/SabreTools.Models/Logiqx/DeviceRef.cs
+++ b/SabreTools.Models/Logiqx/DeviceRef.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("device_ref")]
     public class DeviceRef
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
         
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Logiqx/Dir.cs b/SabreTools.Models/Logiqx/Dir.cs
index 4a563788..75418ec9 100644
--- a/SabreTools.Models/Logiqx/Dir.cs
+++ b/SabreTools.Models/Logiqx/Dir.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("dir")]
     public class Dir
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlElement("game", typeof(Game))]
         [XmlElement("machine", typeof(Machine))]
diff --git a/SabreTools.Models/Logiqx/Disk.cs b/SabreTools.Models/Logiqx/Disk.cs
index 88b56228..957ff810 100644
--- a/SabreTools.Models/Logiqx/Disk.cs
+++ b/SabreTools.Models/Logiqx/Disk.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("disk")]
     public class Disk
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("md5")]
         public string? MD5 { get; set; }
diff --git a/SabreTools.Models/Logiqx/Driver.cs b/SabreTools.Models/Logiqx/Driver.cs
index 2485c552..823605c0 100644
--- a/SabreTools.Models/Logiqx/Driver.cs
+++ b/SabreTools.Models/Logiqx/Driver.cs
@@ -7,20 +7,24 @@ namespace SabreTools.Models.Logiqx
     public class Driver
     {
         /// <remarks>(good|imperfect|preliminary)</remarks>
+        [Required]
         [XmlAttribute("status")]
-        public string Status { get; set; }
+        public string? Status { get; set; }
 
         /// <remarks>(good|imperfect|preliminary)</remarks>
+        [Required]
         [XmlAttribute("emulation")]
-        public string Emulation { get; set; }
+        public string? Emulation { get; set; }
 
         /// <remarks>(good|imperfect|preliminary)</remarks>
+        [Required]
         [XmlAttribute("cocktail")]
-        public string Cocktail { get; set; }
+        public string? Cocktail { get; set; }
 
         /// <remarks>(supported|unsupported)</remarks>
+        [Required]
         [XmlAttribute("savestate")]
-        public string SaveState { get; set; }
+        public string? SaveState { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("requiresartwork")]
diff --git a/SabreTools.Models/Logiqx/GameBase.cs b/SabreTools.Models/Logiqx/GameBase.cs
index b3ae4980..cdaf2409 100644
--- a/SabreTools.Models/Logiqx/GameBase.cs
+++ b/SabreTools.Models/Logiqx/GameBase.cs
@@ -8,8 +8,9 @@ namespace SabreTools.Models.Logiqx
     /// </summary>
     public abstract class GameBase
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("sourcefile")]
         public string? SourceFile { get; set; }
@@ -56,8 +57,9 @@ namespace SabreTools.Models.Logiqx
         [XmlElement("comment")]
         public string[]? Comment { get; set; }
 
+        [Required]
         [XmlElement("description")]
-        public string Description { get; set; }
+        public string? Description { get; set; }
 
         [XmlElement("year")]
         public string? Year { get; set; }
diff --git a/SabreTools.Models/Logiqx/Header.cs b/SabreTools.Models/Logiqx/Header.cs
index ba63d9d9..8dd020b1 100644
--- a/SabreTools.Models/Logiqx/Header.cs
+++ b/SabreTools.Models/Logiqx/Header.cs
@@ -10,11 +10,13 @@ namespace SabreTools.Models.Logiqx
         [XmlElement("id")]
         public string? Id { get; set; }
 
+        [Required]
         [XmlElement("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlElement("description")]
-        public string Description { get; set; }
+        public string? Description { get; set; }
 
         /// <remarks>Trurip extension</remarks>
         [XmlElement("rootdir")]
@@ -23,14 +25,16 @@ namespace SabreTools.Models.Logiqx
         [XmlElement("category")]
         public string? Category { get; set; }
 
+        [Required]
         [XmlElement("version")]
-        public string Version { get; set; }
+        public string? Version { get; set; }
 
         [XmlElement("date")]
         public string? Date { get; set; }
 
+        [Required]
         [XmlElement("author")]
-        public string Author { get; set; }
+        public string? Author { get; set; }
 
         [XmlElement("email")]
         public string? Email { get; set; }
diff --git a/SabreTools.Models/Logiqx/Media.cs b/SabreTools.Models/Logiqx/Media.cs
index deb1f008..d13fdf75 100644
--- a/SabreTools.Models/Logiqx/Media.cs
+++ b/SabreTools.Models/Logiqx/Media.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("media")]
     public class Media
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("md5")]
         public string? MD5 { get; set; }
diff --git a/SabreTools.Models/Logiqx/Release.cs b/SabreTools.Models/Logiqx/Release.cs
index 0210a322..b44fa76b 100644
--- a/SabreTools.Models/Logiqx/Release.cs
+++ b/SabreTools.Models/Logiqx/Release.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("release")]
     public class Release
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("region")]
-        public string Region { get; set; }
+        public string? Region { get; set; }
 
         [XmlAttribute("language")]
         public string? Language { get; set; }
diff --git a/SabreTools.Models/Logiqx/Rom.cs b/SabreTools.Models/Logiqx/Rom.cs
index 525bf289..6866113e 100644
--- a/SabreTools.Models/Logiqx/Rom.cs
+++ b/SabreTools.Models/Logiqx/Rom.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("rom")]
     public class Rom
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("size")]
-        public string Size { get; set; }
+        public string? Size { get; set; }
 
         [XmlAttribute("crc")]
         public string? CRC { get; set; }
diff --git a/SabreTools.Models/Logiqx/Sample.cs b/SabreTools.Models/Logiqx/Sample.cs
index e9c05638..98901f36 100644
--- a/SabreTools.Models/Logiqx/Sample.cs
+++ b/SabreTools.Models/Logiqx/Sample.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("sample")]
     public class Sample
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
         
         #region DO NOT USE IN PRODUCTION
 
diff --git a/SabreTools.Models/Logiqx/SoftwareList.cs b/SabreTools.Models/Logiqx/SoftwareList.cs
index b2e3d91c..36cabc85 100644
--- a/SabreTools.Models/Logiqx/SoftwareList.cs
+++ b/SabreTools.Models/Logiqx/SoftwareList.cs
@@ -6,15 +6,18 @@ namespace SabreTools.Models.Logiqx
     [XmlRoot("softwarelist")]
     public class SoftwareList
     {
+        [Required]
         [XmlAttribute("tag")]
-        public string Tag { get; set; }
+        public string? Tag { get; set; }
 
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         /// <remarks>(original|compatible)</remarks>
+        [Required]
         [XmlAttribute("status")]
-        public string Status { get; set; }
+        public string? Status { get; set; }
 
         [XmlAttribute("filter")]
         public string? Filter { get; set; }
diff --git a/SabreTools.Models/OpenMSX/Software.cs b/SabreTools.Models/OpenMSX/Software.cs
index a86b9b05..29167e15 100644
--- a/SabreTools.Models/OpenMSX/Software.cs
+++ b/SabreTools.Models/OpenMSX/Software.cs
@@ -6,23 +6,28 @@ namespace SabreTools.Models.OpenMSX
     [XmlRoot("software")]
     public class Software
     {
+        [Required]
         [XmlElement("title")]
-        public string Title { get; set; }
+        public string? Title { get; set; }
 
         [XmlElement("genmsxid")]
         public string? GenMSXID { get; set; }
 
+        [Required]
         [XmlElement("system")]
-        public string System { get; set; }
+        public string? System { get; set; }
 
+        [Required]
         [XmlElement("company")]
-        public string Company { get; set; }
+        public string? Company { get; set; }
 
+        [Required]
         [XmlElement("year")]
-        public string Year { get; set; }
+        public string? Year { get; set; }
 
+        [Required]
         [XmlElement("country")]
-        public string Country { get; set; }
+        public string? Country { get; set; }
 
         [XmlElement("dump")]
         public Dump[]? Dump { get; set; }
diff --git a/SabreTools.Models/RequiredAttribute.cs b/SabreTools.Models/RequiredAttribute.cs
new file mode 100644
index 00000000..dfb4eb5c
--- /dev/null
+++ b/SabreTools.Models/RequiredAttribute.cs
@@ -0,0 +1,9 @@
+namespace SabreTools.Models
+{
+    /// <summary>
+    /// Marks a property as required on write
+    /// </summary>
+    /// <remarks>TODO: Use reflection to determine required fields on write</remarks>
+    [System.AttributeUsage(System.AttributeTargets.Property)]
+    public class RequiredAttribute : System.Attribute { }
+}
\ No newline at end of file
diff --git a/SabreTools.Models/SeparatedValue/MetadataFile.cs b/SabreTools.Models/SeparatedValue/MetadataFile.cs
index cc9f81bd..7fddc2eb 100644
--- a/SabreTools.Models/SeparatedValue/MetadataFile.cs
+++ b/SabreTools.Models/SeparatedValue/MetadataFile.cs
@@ -2,7 +2,8 @@ namespace SabreTools.Models.SeparatedValue
 {
     public class MetadataFile
     {
-        public string[] Header { get; set; }
+        [Required]
+        public string[]? Header { get; set; }
 
         public Row[]? Row { get; set; }
     }
diff --git a/SabreTools.Models/SeparatedValue/Row.cs b/SabreTools.Models/SeparatedValue/Row.cs
index 44979ffb..b9f170c1 100644
--- a/SabreTools.Models/SeparatedValue/Row.cs
+++ b/SabreTools.Models/SeparatedValue/Row.cs
@@ -15,13 +15,15 @@ namespace SabreTools.Models.SeparatedValue
         public string? Description { get; set; }
 
         /// <remarks>Game Name</remarks>
-        public string GameName { get; set; }
+        [Required]
+        public string? GameName { get; set; }
 
         /// <remarks>Game Description</remarks>
         public string? GameDescription { get; set; }
 
         /// <remarks>Type</remarks>
-        public string Type { get; set; }
+        [Required]
+        public string? Type { get; set; }
 
         /// <remarks>Rom Name</remarks>
         public string? RomName { get; set; }
diff --git a/SabreTools.Models/SoftwareList/DataArea.cs b/SabreTools.Models/SoftwareList/DataArea.cs
index 6da72615..d58ae7f1 100644
--- a/SabreTools.Models/SoftwareList/DataArea.cs
+++ b/SabreTools.Models/SoftwareList/DataArea.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("dataarea")]
     public class DataArea
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("size")]
-        public string Size { get; set; }
+        public string? Size { get; set; }
         
         /// <remarks>(8|16|32|64) "8"</remarks>
         [XmlAttribute("width")]
diff --git a/SabreTools.Models/SoftwareList/DipSwitch.cs b/SabreTools.Models/SoftwareList/DipSwitch.cs
index 8fbdaf93..2fd6fd3d 100644
--- a/SabreTools.Models/SoftwareList/DipSwitch.cs
+++ b/SabreTools.Models/SoftwareList/DipSwitch.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("dipswitch")]
     public class DipSwitch
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("tag")]
-        public string Tag { get; set; }
+        public string? Tag { get; set; }
 
         [XmlAttribute("mask")]
         public string? Mask { get; set; }
diff --git a/SabreTools.Models/SoftwareList/DipValue.cs b/SabreTools.Models/SoftwareList/DipValue.cs
index 5bbfccfc..1f70bd05 100644
--- a/SabreTools.Models/SoftwareList/DipValue.cs
+++ b/SabreTools.Models/SoftwareList/DipValue.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("dipvalue")]
     public class DipValue
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("value")]
-        public string Value { get; set; }
+        public string? Value { get; set; }
 
         /// <remarks>(yes|no) "no"</remarks>
         [XmlAttribute("default")]
diff --git a/SabreTools.Models/SoftwareList/Disk.cs b/SabreTools.Models/SoftwareList/Disk.cs
index 8090eaae..ca0cbe3d 100644
--- a/SabreTools.Models/SoftwareList/Disk.cs
+++ b/SabreTools.Models/SoftwareList/Disk.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("disk")]
     public class Disk
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("md5")]
         public string? MD5 { get; set; }
diff --git a/SabreTools.Models/SoftwareList/DiskArea.cs b/SabreTools.Models/SoftwareList/DiskArea.cs
index 01b72456..20bba255 100644
--- a/SabreTools.Models/SoftwareList/DiskArea.cs
+++ b/SabreTools.Models/SoftwareList/DiskArea.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("diskarea")]
     public class DiskArea
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlElement("disk")]
         public Disk[]? Disk { get; set; }
diff --git a/SabreTools.Models/SoftwareList/Feature.cs b/SabreTools.Models/SoftwareList/Feature.cs
index 82c8fbf1..2d15ec4e 100644
--- a/SabreTools.Models/SoftwareList/Feature.cs
+++ b/SabreTools.Models/SoftwareList/Feature.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("feature")]
     public class Feature
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("value")]
         public string? Value { get; set; }
diff --git a/SabreTools.Models/SoftwareList/Info.cs b/SabreTools.Models/SoftwareList/Info.cs
index eced145d..b68f5d7e 100644
--- a/SabreTools.Models/SoftwareList/Info.cs
+++ b/SabreTools.Models/SoftwareList/Info.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("info")]
     public class Info
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("value")]
         public string? Value { get; set; }
diff --git a/SabreTools.Models/SoftwareList/Part.cs b/SabreTools.Models/SoftwareList/Part.cs
index 96125aeb..d4ff21f2 100644
--- a/SabreTools.Models/SoftwareList/Part.cs
+++ b/SabreTools.Models/SoftwareList/Part.cs
@@ -6,11 +6,13 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("part")]
     public class Part
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
+        [Required]
         [XmlAttribute("interface")]
-        public string Interface { get; set; }
+        public string? Interface { get; set; }
 
         [XmlElement("feature")]
         public Feature[]? Feature { get; set; }
diff --git a/SabreTools.Models/SoftwareList/Rom.cs b/SabreTools.Models/SoftwareList/Rom.cs
index 16fef098..e738389f 100644
--- a/SabreTools.Models/SoftwareList/Rom.cs
+++ b/SabreTools.Models/SoftwareList/Rom.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("rom")]
     public class Rom
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("size")]
         public string? Size { get; set; }
diff --git a/SabreTools.Models/SoftwareList/SharedFeat.cs b/SabreTools.Models/SoftwareList/SharedFeat.cs
index e0b46e1b..22c1b493 100644
--- a/SabreTools.Models/SoftwareList/SharedFeat.cs
+++ b/SabreTools.Models/SoftwareList/SharedFeat.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("sharedfeat")]
     public class SharedFeat
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("value")]
         public string? Value { get; set; }
diff --git a/SabreTools.Models/SoftwareList/Software.cs b/SabreTools.Models/SoftwareList/Software.cs
index 5fa19bb4..194acd8b 100644
--- a/SabreTools.Models/SoftwareList/Software.cs
+++ b/SabreTools.Models/SoftwareList/Software.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("software")]
     public class Software
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("cloneof")]
         public string? CloneOf { get; set; }
@@ -16,14 +17,17 @@ namespace SabreTools.Models.SoftwareList
         [XmlAttribute("supported")]
         public string? Supported { get; set; }
 
+        [Required]
         [XmlElement("description")]
-        public string Description { get; set; }
+        public string? Description { get; set; }
 
+        [Required]
         [XmlElement("year")]
-        public string Year { get; set; }
+        public string? Year { get; set; }
 
+        [Required]
         [XmlElement("publisher")]
-        public string Publisher { get; set; }
+        public string? Publisher { get; set; }
 
         [XmlElement("notes")]
         public string? Notes { get; set; }
diff --git a/SabreTools.Models/SoftwareList/SoftwareList.cs b/SabreTools.Models/SoftwareList/SoftwareList.cs
index e374574e..8dd27821 100644
--- a/SabreTools.Models/SoftwareList/SoftwareList.cs
+++ b/SabreTools.Models/SoftwareList/SoftwareList.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.SoftwareList
     [XmlRoot("softwarelist")]
     public class SoftwareList
     {
+        [Required]
         [XmlAttribute("name")]
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
         [XmlAttribute("description")]
         public string? Description { get; set; }
@@ -16,7 +17,7 @@ namespace SabreTools.Models.SoftwareList
         public string? Notes { get; set; }
 
         [XmlElement("software")]
-        public Software[] Software { get; set; }
+        public Software[]? Software { get; set; }
 
         #region DO NOT USE IN PRODUCTION