diff --git a/SabreTools.Library/DatFiles/DatHeader.cs b/SabreTools.Library/DatFiles/DatHeader.cs
index 0cd12f12..bdb3368c 100644
--- a/SabreTools.Library/DatFiles/DatHeader.cs
+++ b/SabreTools.Library/DatFiles/DatHeader.cs
@@ -203,14 +203,41 @@ namespace SabreTools.Library.DatFiles
         [JsonProperty("build")]
         public string Build { get; set; }
 
-        // TODO: Implement the following header values:
-        // - romcenter.plugin
-        // - romcenter.rommode (merged|split|unmerged) "split"
-        // - romcenter.biosmode (merged|split|unmerged) "split"
-        // - romcenter.samplemode (merged|unmerged) "merged"
-        // - romcenter.lockrommode (yes|no) "no"
-        // - romcenter.lockbiosmode (yes|no) "no"
-        // - romcenter.locksamplemode (yes|no) "no"
+        /// <summary>
+        /// RomCenter rom mode
+        /// </summary>
+        [JsonProperty("rommode")]
+        public string RomMode { get; set; } // (merged|split|unmerged) "split"
+
+        /// <summary>
+        /// RomCenter bios mode
+        /// </summary>
+        [JsonProperty("biosmode")]
+        public string BiosMode { get; set; } // (merged|split|unmerged) "split"
+
+        /// <summary>
+        /// RomCenter sample mode
+        /// </summary>
+        [JsonProperty("samplemode")]
+        public string SampleMode { get; set; } // (merged|unmerged) "merged"
+
+        /// <summary>
+        /// RomCenter lock rom mode
+        /// </summary>
+        [JsonProperty("lockrommode")]
+        public bool? LockRomMode { get; set; } // (yes|no) "no"
+
+        /// <summary>
+        /// RomCenter lock bios mode
+        /// </summary>
+        [JsonProperty("lockbiosmode")]
+        public bool? LockBiosMode { get; set; } // (yes|no) "no"
+
+        /// <summary>
+        /// RomCenter lock sample mode
+        /// </summary>
+        [JsonProperty("locksamplemode")]
+        public bool? LockSampleMode { get; set; } // (yes|no) "no"
 
         #endregion
 
@@ -229,7 +256,7 @@ namespace SabreTools.Library.DatFiles
         /// <summary>
         /// System
         /// </summary>
-        /// <remarks>Known as "plugin" in RomCenter</remarks>
+        /// <remarks>Known as "plugin" in Logiqx and RomCenter</remarks>
         [JsonProperty("system")]
         public string System { get; set; }
 
@@ -260,7 +287,7 @@ namespace SabreTools.Library.DatFiles
         // TODO: Implement the following header values:
         // - newdat.datversionurl (currently reads and writes to Header.Url, not strictly correct)
         // - newdat.daturl (currently writes to Header.Url, not strictly correct)
-        // - newdat.daturl[fileName] (currently writes to Header.FileName, not strictly correct)
+        // - newdat.daturl[fileName] (currently writes to Header.FileName + ".zip", not strictly correct)
         // - newdat.imurl (currently writes to Header.Url, not strictly correct)
         // - search[...].to.find[operation, value (Int32?)]
         // - search[...].to[value, default (true|false), auto (true, false)]
diff --git a/SabreTools.Library/DatFiles/Json.cs b/SabreTools.Library/DatFiles/Json.cs
index 0c240066..b97f0b90 100644
--- a/SabreTools.Library/DatFiles/Json.cs
+++ b/SabreTools.Library/DatFiles/Json.cs
@@ -234,6 +234,36 @@ namespace SabreTools.Library.DatFiles
                         Header.Build = (Header.Build == null ? content : Header.Build);
                         break;
 
+                    case "rommode":
+                        content = jtr.ReadAsString();
+                        Header.RomMode = (Header.RomMode == null ? content : Header.RomMode);
+                        break;
+
+                    case "biosmode":
+                        content = jtr.ReadAsString();
+                        Header.BiosMode = (Header.BiosMode == null ? content : Header.BiosMode);
+                        break;
+
+                    case "samplemode":
+                        content = jtr.ReadAsString();
+                        Header.Build = (Header.SampleMode == null ? content : Header.SampleMode);
+                        break;
+
+                    case "lockrommode":
+                        content = jtr.ReadAsString();
+                        Header.LockRomMode = (Header.LockRomMode == null ? content.AsYesNo() : Header.LockRomMode);
+                        break;
+
+                    case "lockbiosmode":
+                        content = jtr.ReadAsString();
+                        Header.LockBiosMode = (Header.LockBiosMode == null ? content.AsYesNo() : Header.LockBiosMode);
+                        break;
+
+                    case "locksamplemode":
+                        content = jtr.ReadAsString();
+                        Header.LockSampleMode = (Header.LockSampleMode == null ? content.AsYesNo() : Header.LockSampleMode);
+                        break;
+
                     #endregion
 
                     #region OfflineList
@@ -1141,6 +1171,69 @@ namespace SabreTools.Library.DatFiles
                     jtw.WriteValue(Header.Build);
                 }
 
+                if (!string.IsNullOrWhiteSpace(Header.RomMode))
+                {
+                    jtw.WritePropertyName("rommode");
+                    jtw.WriteValue(Header.RomMode);
+                }
+
+                if (!string.IsNullOrWhiteSpace(Header.BiosMode))
+                {
+                    jtw.WritePropertyName("biosmode");
+                    jtw.WriteValue(Header.BiosMode);
+                }
+
+                if (!string.IsNullOrWhiteSpace(Header.SampleMode))
+                {
+                    jtw.WritePropertyName("samplemode");
+                    jtw.WriteValue(Header.SampleMode);
+                }
+
+                if (Header.LockRomMode != null)
+                {
+                    switch (Header.LockRomMode)
+                    {
+                        case true:
+                            jtw.WritePropertyName("lockrommode");
+                            jtw.WriteValue("yes");
+                            break;
+                        case false:
+                            jtw.WritePropertyName("lockrommode");
+                            jtw.WriteValue("no");
+                            break;
+                    }
+                }
+
+                if (Header.LockBiosMode != null)
+                {
+                    switch (Header.LockBiosMode)
+                    {
+                        case true:
+                            jtw.WritePropertyName("lockbiosmode");
+                            jtw.WriteValue("yes");
+                            break;
+                        case false:
+                            jtw.WritePropertyName("lockbiosmode");
+                            jtw.WriteValue("no");
+                            break;
+                    }
+                }
+
+                if (Header.LockSampleMode != null)
+                {
+                    switch (Header.LockSampleMode)
+                    {
+                        case true:
+                            jtw.WritePropertyName("locksamplemode");
+                            jtw.WriteValue("yes");
+                            break;
+                        case false:
+                            jtw.WritePropertyName("locksamplemode");
+                            jtw.WriteValue("no");
+                            break;
+                    }
+                }
+
                 #endregion
 
                 #region OfflineList
diff --git a/SabreTools.Library/DatFiles/Logiqx.cs b/SabreTools.Library/DatFiles/Logiqx.cs
index b09c1cca..4679d024 100644
--- a/SabreTools.Library/DatFiles/Logiqx.cs
+++ b/SabreTools.Library/DatFiles/Logiqx.cs
@@ -237,35 +237,23 @@ namespace SabreTools.Library.DatFiles
                         if (Header.System == null)
                             Header.System = reader.GetAttribute("plugin");
 
-                        if (reader.GetAttribute("rommode") != null)
-                        {
-                            // (merged|split|unmerged) "split"
-                        }
+                        if (Header.RomMode == null)
+                            Header.RomMode = reader.GetAttribute("rommode");
 
-                        if (reader.GetAttribute("biosmode") != null)
-                        {
-                            // (merged|split|unmerged) "split"
-                        }
+                        if (Header.BiosMode == null)
+                            Header.BiosMode = reader.GetAttribute("biosmode");
 
-                        if (reader.GetAttribute("samplemode") != null)
-                        {
-                            // (merged|unmerged) "merged"
-                        }
+                        if (Header.SampleMode == null)
+                            Header.SampleMode = reader.GetAttribute("samplemode");
 
-                        if (reader.GetAttribute("lockrommode") != null)
-                        {
-                            // (yes|no) "no"
-                        }
+                        if (Header.LockRomMode == null)
+                            Header.LockRomMode = reader.GetAttribute("lockrommode").AsYesNo();
 
-                        if (reader.GetAttribute("lockbiosmode") != null)
-                        {
-                            // (yes|no) "no"
-                        }
+                        if (Header.LockBiosMode == null)
+                            Header.LockBiosMode = reader.GetAttribute("lockbiosmode").AsYesNo();
 
-                        if (reader.GetAttribute("locksamplemode") != null)
-                        {
-                            // (yes|no) "no"
-                        }
+                        if (Header.LockSampleMode == null)
+                            Header.LockSampleMode = reader.GetAttribute("locksamplemode").AsYesNo();
 
                         reader.Read();
                         break;
@@ -863,6 +851,68 @@ namespace SabreTools.Library.DatFiles
                     xtw.WriteEndElement();
                 }
 
+                if (Header.System != null
+                    || Header.RomMode != null || Header.LockRomMode != null
+                    || Header.BiosMode != null || Header.LockBiosMode != null
+                    || Header.SampleMode != null || Header.LockSampleMode != null)
+                {
+                    xtw.WriteStartElement("romcenter");
+
+                    if (!string.IsNullOrWhiteSpace(Header.System))
+                        xtw.WriteAttributeString("plugin", Header.System);
+
+                    if (!string.IsNullOrWhiteSpace(Header.RomMode))
+                        xtw.WriteAttributeString("rommode", Header.RomMode);
+
+                    if (!string.IsNullOrWhiteSpace(Header.BiosMode))
+                        xtw.WriteAttributeString("biosmode", Header.BiosMode);
+
+                    if (!string.IsNullOrWhiteSpace(Header.SampleMode))
+                        xtw.WriteAttributeString("samplemode", Header.SampleMode);
+
+                    if (Header.LockRomMode != null)
+                    {
+                        switch (Header.LockRomMode)
+                        {
+                            case true:
+                                xtw.WriteAttributeString("lockrommode", "yes");
+                                break;
+                            case false:
+                                xtw.WriteAttributeString("lockrommode", "no");
+                                break;
+                        }
+                    }
+
+                    if (Header.LockBiosMode != null)
+                    {
+                        switch (Header.LockBiosMode)
+                        {
+                            case true:
+                                xtw.WriteAttributeString("lockbiosmode", "yes");
+                                break;
+                            case false:
+                                xtw.WriteAttributeString("lockbiosmode", "no");
+                                break;
+                        }
+                    }
+
+                    if (Header.LockSampleMode != null)
+                    {
+                        switch (Header.LockSampleMode)
+                        {
+                            case true:
+                                xtw.WriteAttributeString("locksamplemode", "yes");
+                                break;
+                            case false:
+                                xtw.WriteAttributeString("locksamplemode", "no");
+                                break;
+                        }
+                    }
+
+                    // End romcenter
+                    xtw.WriteEndElement();
+                }
+
                 // End header
                 xtw.WriteEndElement();
 
diff --git a/SabreTools.Library/DatFiles/SeparatedValue.cs b/SabreTools.Library/DatFiles/SeparatedValue.cs
index 86611b5d..20d27c3c 100644
--- a/SabreTools.Library/DatFiles/SeparatedValue.cs
+++ b/SabreTools.Library/DatFiles/SeparatedValue.cs
@@ -206,6 +206,30 @@ namespace SabreTools.Library.DatFiles
                             Header.Build = (Header.Build == null ? value : Header.Build);
                             break;
 
+                        case "DatFile.RomMode":
+                            Header.RomMode = (Header.RomMode == null ? value : Header.RomMode);
+                            break;
+
+                        case "DatFile.BiosMode":
+                            Header.BiosMode = (Header.BiosMode == null ? value : Header.BiosMode);
+                            break;
+
+                        case "DatFile.SampleMode":
+                            Header.SampleMode = (Header.SampleMode == null ? value : Header.SampleMode);
+                            break;
+
+                        case "DatFile.LockRomMode":
+                            Header.LockRomMode = (Header.LockRomMode == null ? value.AsYesNo() : Header.LockRomMode);
+                            break;
+
+                        case "DatFile.LockBiosMode":
+                            Header.LockBiosMode = (Header.LockBiosMode == null ? value.AsYesNo() : Header.LockBiosMode);
+                            break;
+
+                        case "DatFile.LockSampleMode":
+                            Header.LockSampleMode = (Header.LockSampleMode == null ? value.AsYesNo() : Header.LockSampleMode);
+                            break;
+
                         #endregion
 
                         #region OfflineList
@@ -810,6 +834,36 @@ namespace SabreTools.Library.DatFiles
                 case "build":
                     return "DatFile.Build";
 
+                case "rommode":
+                case "rom mode":
+                case "rom-mode":
+                    return "DatFile.RomMode";
+
+                case "biosmode":
+                case "bios mode":
+                case "bios-mode":
+                    return "DatFile.BiosMode";
+
+                case "samplemode":
+                case "sample mode":
+                case "sample-mode":
+                    return "DatFile.SampleMode";
+
+                case "lockrommode":
+                case "lock rom mode":
+                case "lock-rom-mode":
+                    return "DatFile.LockRomMode";
+
+                case "lockbiosmode":
+                case "lock bios mode":
+                case "lock-bios-mode":
+                    return "DatFile.LockBiosMode";
+
+                case "locksamplemode":
+                case "lock sample mode":
+                case "lock-sample-mode":
+                    return "DatFile.LockSampleMode";
+
                 #endregion
 
                 #region OfflineList