diff --git a/LibCmo/CK2/CKContext.cpp b/LibCmo/CK2/CKContext.cpp
index ad9751c..b414d43 100644
--- a/LibCmo/CK2/CKContext.cpp
+++ b/LibCmo/CK2/CKContext.cpp
@@ -99,7 +99,7 @@ namespace LibCmo::CK2 {
 		return 0;
 	}
 
-	MgrImpls::CKBaseManager* CKContext::GetManager(int index) {
+	MgrImpls::CKBaseManager* CKContext::GetManager(CKINT index) {
 		return nullptr;
 	}
 
@@ -188,12 +188,18 @@ namespace LibCmo::CK2 {
 		EncodingHelper::SetStdPathFromU8Path(this->m_TempFolder, u8_temp);
 	}
 
-	FILE* CKContext::OpenTempFile(CKSTRING u8_filename, CKBOOL is_read) {
+	FILE* CKContext::OpenTempFile(CKSTRING u8_filename, CKSTRING u8_mode) {
 		std::filesystem::path stdfilename;
 		EncodingHelper::SetStdPathFromU8Path(stdfilename, u8_filename);
 
 		auto realfile = this->m_TempFolder / stdfilename;
-		return EncodingHelper::OpenStdPathFile(realfile, is_read);
+		return EncodingHelper::StdPathFOpen(realfile, u8_mode);
+	}
+
+	FILE* CKContext::OpenFile(CKSTRING u8_filename, CKSTRING u8_mode) {
+		std::filesystem::path stdfilename;
+		EncodingHelper::SetStdPathFromU8Path(stdfilename, u8_filename);
+		return EncodingHelper::StdPathFOpen(stdfilename, u8_mode);
 	}
 
 #pragma endregion
diff --git a/LibCmo/CK2/CKContext.hpp b/LibCmo/CK2/CKContext.hpp
index af932a9..e941c54 100644
--- a/LibCmo/CK2/CKContext.hpp
+++ b/LibCmo/CK2/CKContext.hpp
@@ -60,7 +60,7 @@ namespace LibCmo::CK2 {
 		// ========== Common Managers Functions ==========
 
 		CKINT GetManagerCount();
-		MgrImpls::CKBaseManager* GetManager(int index);
+		MgrImpls::CKBaseManager* GetManager(CKINT index);
 
 		// ========== File Save/Load Options ==========
 		
@@ -79,7 +79,8 @@ namespace LibCmo::CK2 {
 		// ========== Temp IO utilities ==========
 
 		void SetTempPath(CKSTRING u8_temp);
-		FILE* OpenTempFile(CKSTRING u8_filename, CKBOOL is_read);
+		FILE* OpenTempFile(CKSTRING u8_filename, CKSTRING u8_mode);
+		FILE* OpenFile(CKSTRING u8_filename, CKSTRING u8_mode);
 
 		// ========== Print utilities ==========
 
diff --git a/LibCmo/CK2/CKDefines.hpp b/LibCmo/CK2/CKDefines.hpp
index 56986a2..3950544 100644
--- a/LibCmo/CK2/CKDefines.hpp
+++ b/LibCmo/CK2/CKDefines.hpp
@@ -9,14 +9,19 @@
 #include <functional>
 
 namespace LibCmo::CK2 {
+	/**
+	 * @brief The identifier of Virtools file.
+	*/
+	constexpr const char CKNEMOFI[] = "Nemo Fi";
 	/**
 	 * @brief Current Version of CK Engine (Day/Month/Year)
 	*/
-	constexpr const CKDWORD CKVERSION = 0x05082002u;
+	constexpr const CKDWORD CKVERSION = 0x13022002u;
 	/**
 	 * @brief Current Version of Dev
 	*/
-	constexpr const CKDWORD DEVVERSION = 0x02050000u;
+	constexpr const CKDWORD DEVVERSION = 0x02010001u;
+	constexpr const CKDWORD DEVBUILD = 0u;
 	constexpr const CKGUID VIRTOOLS_GUID = CKGUID(0x56495254u, 0x4f4f4c53u);
 
 	// ========== Class registration utilities ==========
diff --git a/LibCmo/CK2/CKFile.hpp b/LibCmo/CK2/CKFile.hpp
index d8ea959..98f88f1 100644
--- a/LibCmo/CK2/CKFile.hpp
+++ b/LibCmo/CK2/CKFile.hpp
@@ -121,6 +121,7 @@ namespace LibCmo::CK2 {
 		ObjImpls::CKObject* ObjPtr; /**< A pointer to the object itself (as CreatedObject when loading) */
 		TypeHelper::MKString Name; /**< Name of the Object */
 		CKStateChunk* Data; /**< A CKStateChunk that contains object information */
+		CKDWORD PackSize;  /**< The CKStateChunk data size */
 		//CKINT PostPackSize; /**< When compressed chunk by chunk : size of Data after compression */
 		//CKINT PrePackSize; /**< When compressed chunk by chunk : size of Data before compression */
 		CK_FO_OPTIONS Options; /**< When loading an object it may be renamed , use to replace another object */
@@ -233,11 +234,14 @@ namespace LibCmo::CK2 {
 		*/
 		CKBOOL m_IsCopyFromReader;
 		
+		CKINT m_SaveIDMax; /**< Maximum CK_ID found when saving or loading objects */
 		XContainer::XArray<CKFileObject> m_FileObjects; /**< List of objects being saved / loaded */
 		XContainer::XArray<CKFileManagerData> m_ManagersData; /**< Manager Data loaded */
 		XContainer::XArray<CKFilePluginDependencies> m_PluginsDep;	/**< Plugins dependencies for this file */
 		XContainer::XArray<XContainer::XString> m_IncludedFiles; /**< List of files that should be inserted in the CMO file. */
-		CKFileInfo m_FileInfo; /**< Headers summary */
+		//CKFileInfo m_FileInfo; /**< Headers summary */
+
+		CKERROR PrepareFile(CKSTRING filename);
 
 		CKContext* m_Ctx;
 		CKFileVisitor m_Visitor;
diff --git a/LibCmo/CK2/CKFileOthers.cpp b/LibCmo/CK2/CKFileOthers.cpp
index b0bcc22..3d3e8ca 100644
--- a/LibCmo/CK2/CKFileOthers.cpp
+++ b/LibCmo/CK2/CKFileOthers.cpp
@@ -1,5 +1,6 @@
 #include "CKFile.hpp"
 #include "CKStateChunk.hpp"
+#include "ObjImpls/CKObject.hpp"
 #include <cstdarg>
 
 namespace LibCmo::CK2 {
@@ -13,12 +14,12 @@ namespace LibCmo::CK2 {
 	CKFileObject::CKFileObject() :
 		ObjectId(0u), CreatedObjectId(0u), ObjectCid(CK_CLASSID::CKCID_OBJECT),
 		ObjPtr(nullptr), Name(), Data(nullptr), Options(CK_FO_OPTIONS::CK_FO_DEFAULT),
-		FileIndex(0u), SaveFlags(CK_STATESAVE_ALL) {}
+		FileIndex(0u), SaveFlags(CK_STATESAVE_ALL), PackSize(0u) {}
 
 	CKFileObject::CKFileObject(const CKFileObject& rhs) :
 		ObjectId(rhs.ObjectId), CreatedObjectId(rhs.CreatedObjectId), ObjectCid(rhs.ObjectCid),
 		ObjPtr(rhs.ObjPtr), Name(rhs.Name), Data(rhs.Data), Options(rhs.Options),
-		FileIndex(rhs.FileIndex), SaveFlags(rhs.SaveFlags) {
+		FileIndex(rhs.FileIndex), SaveFlags(rhs.SaveFlags), PackSize(rhs.PackSize) {
 		if (this->Data != nullptr) {
 			this->Data = new CKStateChunk(*(rhs.Data));
 		}
@@ -27,7 +28,7 @@ namespace LibCmo::CK2 {
 	CKFileObject::CKFileObject(CKFileObject&& rhs) :
 		ObjectId(rhs.ObjectId), CreatedObjectId(rhs.CreatedObjectId), ObjectCid(rhs.ObjectCid),
 		ObjPtr(rhs.ObjPtr), Name(rhs.Name), Data(rhs.Data), Options(rhs.Options),
-		FileIndex(rhs.FileIndex), SaveFlags(rhs.SaveFlags) {
+		FileIndex(rhs.FileIndex), SaveFlags(rhs.SaveFlags), PackSize(rhs.PackSize) {
 		rhs.Data = nullptr;
 	}
 
@@ -43,6 +44,7 @@ namespace LibCmo::CK2 {
 			this->Data = new CKStateChunk(*(rhs.Data));
 		}
 
+		this->PackSize = rhs.PackSize;
 		this->Options = rhs.Options;
 		this->FileIndex = rhs.FileIndex;
 		this->SaveFlags = rhs.SaveFlags;
@@ -59,7 +61,8 @@ namespace LibCmo::CK2 {
 
 		this->Data = rhs.Data;
 		rhs.Data = nullptr;
-
+		
+		this->PackSize = rhs.PackSize;
 		this->Options = rhs.Options;
 		this->FileIndex = rhs.FileIndex;
 		this->SaveFlags = rhs.SaveFlags;
@@ -160,16 +163,19 @@ namespace LibCmo::CK2 {
 	CKFileWriter::CKFileWriter(CKContext* ctx) :
 		m_Ctx(ctx), m_Visitor(this),
 		m_Done(false), m_IsCopyFromReader(false),
-		m_FileObjects(), m_ManagersData(), m_PluginsDep(), m_IncludedFiles(),
-		m_FileInfo()
+		m_SaveIDMax(0),
+		m_FileObjects(), m_ManagersData(), m_PluginsDep(), m_IncludedFiles()
 	{}
 
 	CKFileWriter::CKFileWriter(CKContext* ctx, CKFileReader* reader) :
 		m_Ctx(ctx), m_Visitor(this),
 		m_Done(false), m_IsCopyFromReader(true),
-		m_FileObjects(), m_ManagersData(), m_PluginsDep(), m_IncludedFiles(),
-		m_FileInfo()
+		m_SaveIDMax(0),
+		m_FileObjects(), m_ManagersData(), m_PluginsDep(), m_IncludedFiles()
 	{
+		// sync save id max
+		this->m_SaveIDMax = reader->GetSaveIdMax();
+
 		// copy objects
 		for (const auto& item : reader->GetFileObjects()) {
 			CKFileObject obj;
@@ -182,8 +188,11 @@ namespace LibCmo::CK2 {
 				obj.Data = new CKStateChunk(*item.Data);
 			}
 
-			// copy save flag
+			// copy other data
+			obj.ObjectId = item.ObjectId;
+			obj.ObjectCid = item.ObjectCid;
 			obj.SaveFlags = item.SaveFlags;
+			obj.Name = item.Name;
 
 			// insert
 			m_FileObjects.emplace_back(std::move(obj));
diff --git a/LibCmo/CK2/CKFileReader.cpp b/LibCmo/CK2/CKFileReader.cpp
index f3fbd1a..6e984a7 100644
--- a/LibCmo/CK2/CKFileReader.cpp
+++ b/LibCmo/CK2/CKFileReader.cpp
@@ -16,7 +16,7 @@ namespace LibCmo::CK2 {
 
 	CKERROR CKFileReader::ShallowLoad(CKSTRING u8_filename) {
 		// check document status
-		if (this->m_Done) LIBPANIC("Can not load multiple times for single CKFileReader.")
+		if (this->m_Done) CKERROR::CKERR_CANCELLED;
 
 		// check file and open memory
 		if (u8_filename == nullptr) return CKERROR::CKERR_INVALIDPARAMETER;
@@ -46,7 +46,7 @@ namespace LibCmo::CK2 {
 		// ========== read header ==========
 		// check header size
 		if (parser->GetSize() < sizeof(CKRawFileInfo)) return CKERROR::CKERR_INVALIDFILE;
-		if (std::memcmp(parser->GetPtr(), "Nemo Fi", sizeof(CKRawFileInfo::NeMo))) return CKERROR::CKERR_INVALIDFILE;
+		if (std::memcmp(parser->GetPtr(), CKNEMOFI, sizeof(CKRawFileInfo::NeMo))) return CKERROR::CKERR_INVALIDFILE;
 		// read header
 		CKRawFileInfo rawHeader;
 		parser->Read(&rawHeader, sizeof(CKRawFileInfo));
@@ -168,7 +168,7 @@ namespace LibCmo::CK2 {
 				parser->Read(&includedFileCount, sizeof(CKDWORD));
 				this->m_IncludedFiles.resize(includedFileCount);
 
-				hasIncludedFile -= 4;
+				hasIncludedFile -= sizeof(CKDWORD);
 			}
 
 			// MARK: backward pos
@@ -263,13 +263,12 @@ namespace LibCmo::CK2 {
 		// only works file version >= 4. < 4 section has been removed.
 		if (this->m_FileInfo.ObjectCount != 0) {
 			// new file reader section
-			CKDWORD stateChunkLen = 0u;
 			bool stateChkParseSuccess = false;
 			for (auto& obj : this->m_FileObjects) {
 				// get statechunk len
-				parser->Read(&stateChunkLen, sizeof(CKDWORD));
+				parser->Read(&obj.PackSize, sizeof(CKDWORD));
 				// check state chunk len
-				if (stateChunkLen == 0) {
+				if (obj.PackSize == 0) {
 					obj.Data = nullptr;
 					continue;
 				}
@@ -281,7 +280,7 @@ namespace LibCmo::CK2 {
 					delete obj.Data;
 					obj.Data = nullptr;
 				}
-				parser->MoveCursor(stateChunkLen);
+				parser->MoveCursor(obj.PackSize);
 
 			}
 		}
@@ -311,7 +310,7 @@ namespace LibCmo::CK2 {
 				parser->Read(&filebodylen, sizeof(CKDWORD));
 
 				// read file body
-				FILE* fp = m_Ctx->OpenTempFile(file.c_str(), false);
+				FILE* fp = m_Ctx->OpenTempFile(file.c_str(), "wb");
 				if (fp != nullptr) {
 					StreamHelper::CopyStream(parser->GetPtr(), fp, filebodylen);
 					fclose(fp);
@@ -326,6 +325,9 @@ namespace LibCmo::CK2 {
 	}
 
 	CKERROR CKFileReader::DeepLoad(CKSTRING u8_filename) {
+		// check document status
+		if (this->m_Done) CKERROR::CKERR_CANCELLED;
+
 		// ========== prepare work ==========
 		CKERROR err = CKERROR::CKERR_OK;
 
diff --git a/LibCmo/CK2/CKFileWriter.cpp b/LibCmo/CK2/CKFileWriter.cpp
index c2dd28a..0211429 100644
--- a/LibCmo/CK2/CKFileWriter.cpp
+++ b/LibCmo/CK2/CKFileWriter.cpp
@@ -1,9 +1,212 @@
 #include "CKFile.hpp"
+#include "CKContext.hpp"
+#include "CKStateChunk.hpp"
+#include "ObjImpls/CKObject.hpp"
+#include "MgrImpls/CKBaseManager.hpp"
+#include "../VxMath/VxMemoryMappedFile.hpp"
+#include <memory>
 
 namespace LibCmo::CK2 {
 
 	CKERROR CKFileWriter::Save(CKSTRING u8_filename) {
-		return CKERROR::CKERR_OK;
+		// check document status
+		if (this->m_Done) CKERROR::CKERR_CANCELLED;
+
+		// try detect filename legality
+		CKERROR err = PrepareFile(u8_filename);
+		if (err != CKERROR::CKERR_OK) return err;
+		
+		// ========== Prepare Stage ==========
+		// todo: add TOBEDELETED flag for all Referenced objects's m_ObjectFlags
+
+		// MARK: ignore the notification to all CKBehavior based objects.
+
+		// ========== StateChunk convertion ==========
+		
+		// iterate all objects and transform it into CKStateChunk
+		// MARK: Drop the support of collecting the sum of InterfaceChunk's size.
+		// because it is useless.
+		for (auto& obj : m_FileObjects) {
+			// if there is a chunk, skip
+			if (obj.Data != nullptr) continue;
+
+			obj.Data = new CKStateChunk(&m_Visitor, m_Ctx);
+			obj.Data->StartWrite();
+			bool suc = obj.ObjPtr->Save(obj.Data, &m_Visitor, obj.SaveFlags);
+			obj.Data->StopWrite();
+			if (!suc) {
+				// fail to parse
+				delete obj.Data;
+				obj.Data = nullptr;
+			}
+		}
+
+		// iterate manager
+		// if copied from reader. skip
+		if (!m_IsCopyFromReader) {
+			CKINT mgrcount = m_Ctx->GetManagerCount();
+			CKINT availablemgr = 0;
+
+			// place manager
+			// if no data, skip it
+			m_ManagersData.resize(mgrcount);
+			for (CKINT i = 0; i < mgrcount; ++i) {
+				MgrImpls::CKBaseManager* mgr = m_Ctx->GetManager(i);
+
+				m_ManagersData[availablemgr].Manager = mgr->GetGuid();
+
+				m_ManagersData[availablemgr].Data = new CKStateChunk(&m_Visitor, m_Ctx);
+				m_ManagersData[availablemgr].Data->StartWrite();
+				bool suc = mgr->SaveData(m_ManagersData[availablemgr].Data, &m_Visitor);
+				m_ManagersData[availablemgr].Data->StopWrite();
+				if (!suc) {
+					delete m_ManagersData[availablemgr].Data;
+					m_ManagersData[availablemgr].Data = nullptr;
+				} else {
+					++availablemgr;
+				}
+			}
+			// resize to the new size which erase all skipped manager
+			m_ManagersData.resize(availablemgr);
+
+		}
+
+		// if copied from reader, skip plugin dep
+		if (!m_IsCopyFromReader) {
+			// todo: finish plugin dep filling
+		}
+
+		// MARK: skip include file filling.
+		// we order user manually fill it.
+
+		// ========== Size Calc ==========
+		// iterate 3 list to get each parts' size
+		CKDWORD sumDataObjSize = 0,
+			sumHdrObjSize = 0;
+		for (auto& obj : m_FileObjects) {
+			// += 4DWORD(ObjId, ObjCid, FileIndex, NameLen) + Name size
+			sumHdrObjSize += 4 * sizeof(CKDWORD) + obj.Name.size();
+
+			if (obj.Data == nullptr) {
+				obj.PackSize = 0;
+			} else {
+				obj.PackSize = obj.Data->ConvertToBuffer(nullptr);
+			}
+			// += chunk size + chunk
+			sumDataObjSize += obj.PackSize + sizeof(CKDWORD);
+		}
+
+		CKDWORD sumDataMgrSize = 0;
+		for (auto& mgr : m_ManagersData) {
+			CKDWORD chunksize;
+			if (mgr.Data == nullptr) {
+				chunksize = 0;
+			} else {
+				chunksize = mgr.Data->ConvertToBuffer(nullptr);
+			}
+			// += GUID(2 DWORD) + chunk size + chunk
+			sumDataMgrSize += chunksize + 3 * sizeof(CKDWORD);
+		}
+
+		// += Plugin Dep list size
+		CKDWORD sumHdrPlgSize = sizeof(CKDWORD);
+		for (auto& plg : m_PluginsDep) {
+			// += GUID list + (dep category + GUID list size)
+			sumHdrPlgSize += sizeof(CKGUID) * plg.m_Guids.size() + 2 * sizeof(CKDWORD);
+		}
+
+		CKDWORD sumHdrIncludedFiles = sizeof(int32_t) + sizeof(CKDWORD);
+
+		// calc the whole size
+		CKDWORD sumHdrSize = sumHdrObjSize + sumHdrPlgSize + sumHdrIncludedFiles;
+		CKDWORD sumDataSize = sumDataObjSize + sumDataMgrSize;
+
+		// compute file index for all object
+		if (!m_FileObjects.empty()) {
+			// set base for first one
+			m_FileObjects[0].FileIndex = sumHdrSize + sumDataMgrSize + sizeof(CKRawFileInfo);
+			// calc the remains
+			for (size_t i = 1; i < m_FileObjects.size(); ++i) {
+				// prev obj PackSize + prev obj FileIndex + prev obj chunk size
+				m_FileObjects[i].FileIndex = m_FileObjects[i - 1].FileIndex +  m_FileObjects[i - 1].PackSize + sizeof(CKDWORD);
+			}
+		}
+
+		// ========== Construct File Header ==========
+		CKRawFileInfo rawHeader;
+		std::memcpy(&rawHeader.NeMo, CKNEMOFI, sizeof(CKRawFileInfo::NeMo));
+		rawHeader.Crc = 0;
+		rawHeader.Zero = 0;
+		rawHeader.CKVersion = CKVERSION;
+		rawHeader.FileVersion = 8;
+		rawHeader.FileWriteMode = static_cast<CKDWORD>(m_Ctx->GetFileWriteMode());
+		rawHeader.ObjectCount = static_cast<CKDWORD>(m_FileObjects.size());
+		rawHeader.ManagerCount = static_cast<CKDWORD>(m_ManagersData.size());
+		rawHeader.Hdr1UnPackSize = sumHdrSize;
+		rawHeader.DataUnPackSize = sumDataSize;
+		rawHeader.Hdr1PackSize = sumHdrSize;
+		rawHeader.DataPackSize = sumDataSize;
+		rawHeader.ProductVersion = DEVVERSION;
+		rawHeader.ProductBuild = DEVBUILD;
+		rawHeader.MaxIDSaved = m_SaveIDMax;
+		// crc will filled later
+
+		// create a encoding conversion helper string
+		std::string name_conv;
+
+		// ========== Writing header ==========
+		// create a buffer
+		std::unique_ptr<CKBufferParser> hdrparser(new CKBufferParser(sumHdrSize));
+
+		// write obj
+		for (auto& obj : m_FileObjects) {
+
+			// todo: remove TOBEDELETED for referenced objects' m_ObjectFlags
+
+			hdrparser->Write(&obj.ObjectId, sizeof(CK_ID));
+			hdrparser->Write(&obj.ObjectCid, sizeof(CK_CLASSID));
+			hdrparser->Write(&obj.FileIndex, sizeof(CKDWORD));
+
+			if (obj.Name.c_str() != nullptr) {
+				m_Ctx->GetNativeString(obj.Name.string(), name_conv);
+				CKDWORD namelen = static_cast<CKDWORD>(name_conv.size());
+				hdrparser->Write(&namelen, sizeof(CKDWORD));
+				hdrparser->Write(name_conv.data(), namelen);
+			}
+		}
+
+		// write plugin dep
+		{
+			CKDWORD depsize = static_cast<CKDWORD>(m_PluginsDep.size());
+			hdrparser->Write(&depsize, sizeof(CKDWORD));
+
+			for (auto& dep : m_PluginsDep) {
+				hdrparser->Write(&dep.m_PluginCategory, sizeof(CK_PLUGIN_TYPE));
+
+				CKDWORD guidsize = static_cast<CKDWORD>(dep.m_Guids.size());
+				hdrparser->Write(&guidsize, sizeof(CKDWORD));
+
+				hdrparser->Write(dep.m_Guids.data(), sizeof(CKGUID) * guidsize);
+			}
+		}
+
+	}
+
+	CKERROR CKFileWriter::PrepareFile(CKSTRING filename) {
+		// check nullptr
+		if (filename == nullptr) return CKERROR::CKERR_INVALIDFILE;
+		
+		// try open file to check whether we can write it.
+		CKERROR err;
+		FILE* tryfile = m_Ctx->OpenFile(filename, "ab");
+		if (tryfile == nullptr) {
+			err = CKERROR::CKERR_CANTWRITETOFILE;
+		} else {
+			err = CKERROR::CKERR_OK;
+			std::fclose(tryfile);
+		}
+
+		return err;
 	}
 
 }
\ No newline at end of file
diff --git a/LibCmo/CK2/CKGlobals.hpp b/LibCmo/CK2/CKGlobals.hpp
index 6a2aae3..de31d93 100644
--- a/LibCmo/CK2/CKGlobals.hpp
+++ b/LibCmo/CK2/CKGlobals.hpp
@@ -46,10 +46,12 @@ namespace LibCmo::CK2 {
 	CKDWORD CKComputeDataCRC(const void* data, CKINT size, CKDWORD PreviousCRC = 0);
 
 	// ========== CKClass Registration ==========
+
 	void CKClassRegister(CK_CLASSID cid, CK_CLASSID parentCid,
 		CKClassCreationFct createFct, CKClassReleaseFct relFct, CKClassNameFct nameFct);
 
 	// ========== Class Hierarchy Management ==========
+
 	CKINT CKGetClassCount();
 	const CKClassDesc* CKGetClassDesc(CK_CLASSID cid);
 	CKSTRING CKClassIDToString(CK_CLASSID cid);
diff --git a/LibCmo/CK2/MgrImpls/CKBaseManager.hpp b/LibCmo/CK2/MgrImpls/CKBaseManager.hpp
index 7592ba5..46fe30a 100644
--- a/LibCmo/CK2/MgrImpls/CKBaseManager.hpp
+++ b/LibCmo/CK2/MgrImpls/CKBaseManager.hpp
@@ -69,8 +69,8 @@ namespace LibCmo::CK2::MgrImpls {
 			data for your manager.
 		@see CKStateChunk, LoadData
 		*/
-		virtual CKStateChunk* SaveData(CKFileVisitor* SavedFile) {
-			return nullptr;
+		virtual bool SaveData(CKStateChunk* chunk, CKFileVisitor* SavedFile) {
+			return true;
 		}
 		/**
 		@brief Called to load manager data.
diff --git a/LibCmo/CK2/ObjImpls/CKObject.cpp b/LibCmo/CK2/ObjImpls/CKObject.cpp
index d5751aa..41d78b0 100644
--- a/LibCmo/CK2/ObjImpls/CKObject.cpp
+++ b/LibCmo/CK2/ObjImpls/CKObject.cpp
@@ -6,8 +6,8 @@ namespace LibCmo::CK2::ObjImpls {
 
 	void CKObject::PreSave(CKFileVisitor* file, CKDWORD flags) {}
 
-	CKStateChunk* CKObject::Save(CKFileVisitor* file, CKDWORD flags) {
-		return nullptr;
+	bool CKObject::Save(CKStateChunk* chunk, CKFileVisitor* file, CKDWORD flags) {
+		return true;
 	}
 
 	bool CKObject::Load(CKStateChunk* chunk, CKFileVisitor* file) {
diff --git a/LibCmo/CK2/ObjImpls/CKObject.hpp b/LibCmo/CK2/ObjImpls/CKObject.hpp
index 4b3985d..e42282f 100644
--- a/LibCmo/CK2/ObjImpls/CKObject.hpp
+++ b/LibCmo/CK2/ObjImpls/CKObject.hpp
@@ -40,7 +40,7 @@ namespace LibCmo::CK2::ObjImpls {
 		}
 
 		virtual void PreSave(CKFileVisitor* file, CKDWORD flags);
-		virtual CKStateChunk* Save(CKFileVisitor* file, CKDWORD flags);
+		virtual bool Save(CKStateChunk* chunk, CKFileVisitor* file, CKDWORD flags);
 		virtual bool Load(CKStateChunk* chunk, CKFileVisitor* file);
 		virtual void PostLoad();
 
diff --git a/LibCmo/VTEncoding.cpp b/LibCmo/VTEncoding.cpp
index 10e7b97..69f3c6c 100644
--- a/LibCmo/VTEncoding.cpp
+++ b/LibCmo/VTEncoding.cpp
@@ -187,9 +187,15 @@ namespace LibCmo::EncodingHelper {
 			stdpath = u8_path;
 		}
 	}
-
-	FILE* OpenStdPathFile(std::filesystem::path& u8_filepath, bool is_read) {
-		return _wfopen(u8_filepath.wstring().c_str(), is_read ? L"rb" : L"wb");
+	
+	FILE* StdPathFOpen(std::filesystem::path& std_filepath, const char* u8_mode) {
+		std::wstring wmode;
+		if (CharToWchar(u8_mode, wmode, CP_UTF8)) {
+			return _wfopen(std_filepath.wstring().c_str(), wmode.c_str());
+		} else {
+			// fallback
+			return std::fopen(std_filepath.string().c_str(), u8_mode);
+		}
 	}
 
 #else
@@ -237,8 +243,8 @@ namespace LibCmo::EncodingHelper {
 		stdpath = u8_path;
 	}
 
-	FILE* OpenStdPathFile(std::filesystem::path& u8_filepath, bool is_read) {
-		return fopen(u8_filepath.string().c_str(), is_read ? "rb" : "wb");
+	FILE* StdPathFOpen(std::filesystem::path& std_filepath, const char* u8_mode) {
+		return std::fopen(u8_filepath.string().c_str(), u8_mode);
 	}
 
 
diff --git a/LibCmo/VTEncoding.hpp b/LibCmo/VTEncoding.hpp
index 173a104..193217e 100644
--- a/LibCmo/VTEncoding.hpp
+++ b/LibCmo/VTEncoding.hpp
@@ -72,7 +72,7 @@ namespace LibCmo::EncodingHelper {
 	bool GetNativeVirtoolsName(const std::string& u8_name, std::string& native_name, const ENCODING_TOKEN& token);
 
 	void SetStdPathFromU8Path(std::filesystem::path& stdpath, const char* u8_path);
-	FILE* OpenStdPathFile(std::filesystem::path& u8_filepath, bool is_read);
+	FILE* StdPathFOpen(std::filesystem::path& std_filepath, const char* u8_mode);
 
 #pragma endregion
 
diff --git a/LibCmo/VTUtils.hpp b/LibCmo/VTUtils.hpp
index d750cbf..8c27bb9 100644
--- a/LibCmo/VTUtils.hpp
+++ b/LibCmo/VTUtils.hpp
@@ -119,7 +119,9 @@ namespace LibCmo {
 			const char* c_str() const {
 				return m_HasStr ? m_Str.c_str() : nullptr;
 			}
-
+			const std::string& string() const {
+				return m_Str;
+			}
 			const size_t size() const {
 				return m_HasStr ? m_Str.size() : 0u;
 			}