diff --git a/SabreTools.Library/Filtering/ExtraIni.cs b/SabreTools.Library/Filtering/ExtraIni.cs
new file mode 100644
index 00000000..6c91e3ae
--- /dev/null
+++ b/SabreTools.Library/Filtering/ExtraIni.cs
@@ -0,0 +1,12 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Library.Filtering
+{
+    public class ExtraIni
+    {
+        /// <summary>
+        /// List of extras to apply
+        /// </summary>
+        public List<ExtraIniItem> Items { get; set; } = new List<ExtraIniItem>();
+    }
+}
diff --git a/SabreTools.Library/Filtering/ExtraIniItem.cs b/SabreTools.Library/Filtering/ExtraIniItem.cs
new file mode 100644
index 00000000..21cdedf6
--- /dev/null
+++ b/SabreTools.Library/Filtering/ExtraIniItem.cs
@@ -0,0 +1,123 @@
+using System;
+using System.Collections.Generic;
+
+using SabreTools.Library.Data;
+using SabreTools.Library.DatItems;
+using SabreTools.Library.IO;
+using SabreTools.Library.Tools;
+
+namespace SabreTools.Library.Filtering
+{
+    public class ExtraIniItem
+    {
+        #region Fields
+
+        /// <summary>
+        /// Field to update with INI information
+        /// </summary>
+        public Field Field { get; set; }
+
+        /// <summary>
+        /// Mappings from value to machine name
+        /// </summary>
+        public Dictionary<string, List<string>> Mappings { get; set; } = new Dictionary<string, List<string>>();
+
+        #endregion
+
+        #region Extras Population
+
+        /// <summary>
+        /// Populate item using a field:file input
+        /// </summary>
+        /// <param name="ini">Field and file combination</param>
+        public void PopulateFromInput(string ini)
+        {
+            // If we don't even have a possible field and file combination
+            if (!ini.Contains(":"))
+            {
+                Globals.Logger.Warning($"'{ini}` is not a valid INI extras string. Valid INI extras strings are of the form 'key:value'. Please refer to README.1ST or the help feature for more details.");
+                return;
+            }
+
+            string iniTrimmed = ini.Trim('"', ' ', '\t');
+            string iniFieldString = iniTrimmed.Split(':')[0].ToLowerInvariant().Trim('"', ' ', '\t');
+            string iniFileString = iniTrimmed.Substring(iniFieldString.Length + 1).Trim('"', ' ', '\t');
+
+            Field = iniFieldString.AsField();
+            PopulateFromFile(iniFileString);
+        }
+
+        /// <summary>
+        /// Populate the dictionary from an INI file
+        /// </summary>
+        /// <param name="ini">Path to INI file to populate from</param>
+        /// <remarks>
+        /// The INI file format that is supported here is not exactly the same
+        /// as a traditional one. This expects a MAME extras format, which usually
+        /// doesn't contain key value pairs and always at least contains one section
+        /// called `ROOT_FOLDER`. If that's the name of a section, then we assume
+        /// the value is boolean. If there's another section name, then that is set
+        /// as the value instead.
+        /// </remarks>
+        public void PopulateFromFile(string ini)
+        {
+            // Prepare all intenral variables
+            IniReader ir = ini.GetIniReader(false);
+            bool foundRootFolder = false;
+
+            // If we got a null reader, just return
+            if (ir == null)
+                return;
+
+            // Otherwise, read the file to the end
+            try
+            {
+                ir.ReadNextLine();
+                while (!ir.EndOfStream)
+                {
+                    // We don't care about whitespace or comments
+                    if (ir.RowType == IniRowType.None || ir.RowType == IniRowType.Comment)
+                    {
+                        ir.ReadNextLine();
+                        continue;
+                    }
+
+                    // If we have a section, just read it in
+                    if (ir.RowType == IniRowType.SectionHeader)
+                    {
+                        ir.ReadNextLine();
+
+                        // If we've found the start of the extras, set the flag
+                        if (string.Equals(ir.Section, "ROOT_FOLDER", StringComparison.OrdinalIgnoreCase))
+                            foundRootFolder = true;
+
+                        continue;
+                    }
+
+                    // If we have a value, then we start populating the dictionary
+                    else if (foundRootFolder)
+                    {
+                        // Get the key and value
+                        string key = ir.Section;
+                        string value = ir.Line.Trim();
+
+                        // Ensure the key exists
+                        if (!Mappings.ContainsKey(key))
+                            Mappings[key] = new List<string>();
+
+                        // Add the new mapping
+                        Mappings[key].Add(value);
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                Globals.Logger.Warning($"Exception found while parsing '{ini}': {ex}");
+            }
+
+            ir.Dispose();
+        }
+
+        #endregion
+    }
+}