diff --git a/LibCmo/CK2/CKContext.cpp b/LibCmo/CK2/CKContext.cpp
index 3f0764c..af76e64 100644
--- a/LibCmo/CK2/CKContext.cpp
+++ b/LibCmo/CK2/CKContext.cpp
@@ -1,5 +1,6 @@
 #include "CKContext.hpp"
 #include "ObjImpls/CKObject.hpp"
+#include "../XContainer/XBitArray.hpp"
 #include <cstdarg>
 
 namespace LibCmo::CK2 {
@@ -10,6 +11,29 @@ namespace LibCmo::CK2 {
 	static char g_UniqueFolder[] = "LibCmo";
 #endif
 
+#pragma region Ctor Dtor
+
+	CKContext::CKContext() :
+		m_ObjectsList(), m_ReturnedObjectIds(),
+		m_GroupGlobalIndex(), m_SceneGlobalIndex(),
+		m_CompressionLevel(5), m_FileWriteMode(CK_FILE_WRITEMODE::CKFILE_UNCOMPRESSED),
+		m_NameEncoding(), m_TempFolder(),
+		m_OutputCallback(nullptr)
+	{
+		// preset for temp folder
+		// todo: add current CKContext pointer as the part of temp path.
+		// thus multiple CKContext can work.
+		m_TempFolder = std::filesystem::temp_directory_path();
+		m_TempFolder /= g_UniqueFolder;
+		std::filesystem::create_directory(m_TempFolder);
+	}
+
+	CKContext::~CKContext() {
+		DestroyAllCKObjects();
+	}
+
+#pragma endregion
+
 #pragma region Objects Management
 
 	ObjImpls::CKObject* CKContext::CreateCKObject(CK_CLASSID cls, CKSTRING name,
@@ -78,6 +102,45 @@ namespace LibCmo::CK2 {
 
 	}
 
+	CKDWORD CKContext::AllocateGroupGlobalIndex() {
+		// try find first non-true position
+		CKDWORD index;
+		if (!XContainer::XBitArrayPatch::GetSetBitPosition(m_GroupGlobalIndex, 0, index)) {
+			// failed. distribute new one
+			index = static_cast<CKDWORD>(m_GroupGlobalIndex.size());
+			m_GroupGlobalIndex.resize(m_GroupGlobalIndex.size() + 1);
+		}
+		
+		// set to occupy
+		m_GroupGlobalIndex[index] = true;
+		return index;
+	}
+
+	CKDWORD CKContext::AllocateSceneGlobalIndex() {
+		// same as group
+		CKDWORD index;
+		if (!XContainer::XBitArrayPatch::GetSetBitPosition(m_SceneGlobalIndex, 0, index)) {
+			index = static_cast<CKDWORD>(m_SceneGlobalIndex.size());
+			m_SceneGlobalIndex.resize(m_SceneGlobalIndex.size() + 1);
+		}
+		
+		m_SceneGlobalIndex[index] = true;
+		return index;
+	}
+
+	void CKContext::FreeGroupGlobalIndex(CKDWORD id) {
+		// check position
+		if (id >= m_GroupGlobalIndex.size()) return;
+		// set value
+		m_GroupGlobalIndex[id] = false;
+	}
+
+	void CKContext::FreeSceneGlobalIndex(CKDWORD id) {
+		// same as group
+		if (id >= m_SceneGlobalIndex.size()) return;
+		m_SceneGlobalIndex[id] = false;
+	}
+	
 	void CKContext::DestroyAllCKObjects() {
 		// free all created objects
 		for (auto& ptr : m_ObjectsList) {
@@ -89,6 +152,10 @@ namespace LibCmo::CK2 {
 		m_ReturnedObjectIds.clear();
 		// empty object list
 		m_ObjectsList.clear();
+
+		// clear group and scene global index at the same time
+		m_SceneGlobalIndex.clear();
+		m_GroupGlobalIndex.clear();
 	}
 
 #pragma endregion
@@ -128,29 +195,6 @@ namespace LibCmo::CK2 {
 
 #pragma endregion
 
-
-#pragma region Ctor Dtor
-
-	CKContext::CKContext() :
-		m_ObjectsList(), m_ReturnedObjectIds(),
-		m_CompressionLevel(5), m_FileWriteMode(CK_FILE_WRITEMODE::CKFILE_UNCOMPRESSED),
-		m_NameEncoding(), m_TempFolder(),
-		m_OutputCallback(nullptr)
-	{
-		// preset for temp folder
-		// todo: add current CKContext pointer as the part of temp path.
-		// thus multiple CKContext can work.
-		m_TempFolder = std::filesystem::temp_directory_path();
-		m_TempFolder /= g_UniqueFolder;
-		std::filesystem::create_directory(m_TempFolder);
-	}
-
-	CKContext::~CKContext() {
-		DestroyAllCKObjects();
-	}
-
-#pragma endregion
-
 #pragma region Output utilities
 
 	void CKContext::OutputToConsole(CKSTRING str) {
diff --git a/LibCmo/CK2/CKContext.hpp b/LibCmo/CK2/CKContext.hpp
index 882ae25..4abaacb 100644
--- a/LibCmo/CK2/CKContext.hpp
+++ b/LibCmo/CK2/CKContext.hpp
@@ -42,6 +42,12 @@ namespace LibCmo::CK2 {
 			CK_CREATIONMODE* res = nullptr);
 		ObjImpls::CKObject* GetCKObject(CK_ID id);
 		void DestroyCKObject(CK_ID id);
+
+		CKDWORD AllocateGroupGlobalIndex();
+		CKDWORD AllocateSceneGlobalIndex();
+		void FreeGroupGlobalIndex(CKDWORD id);
+		void FreeSceneGlobalIndex(CKDWORD id);
+
 		void DestroyAllCKObjects();
 
 		// ========== Object Access ==========
@@ -94,6 +100,9 @@ namespace LibCmo::CK2 {
 		XContainer::XArray<ObjImpls::CKObject*> m_ObjectsList;
 		std::deque<CK_ID> m_ReturnedObjectIds;
 
+		XContainer::XBitArray m_GroupGlobalIndex;
+		XContainer::XBitArray m_SceneGlobalIndex;
+
 		// ========== File Save/Load Options ==========
 		CKINT m_CompressionLevel;
 		CK_FILE_WRITEMODE m_FileWriteMode;
diff --git a/LibCmo/CK2/CKDefines.hpp b/LibCmo/CK2/CKDefines.hpp
index a6b5da3..358f7ce 100644
--- a/LibCmo/CK2/CKDefines.hpp
+++ b/LibCmo/CK2/CKDefines.hpp
@@ -34,6 +34,7 @@ namespace LibCmo::CK2 {
 	//using CKClassDependenciesCountFct = std::function<CKINT(CKINT)>;
 
 	struct CKClassDesc {
+		bool IsValid; /**< True if this CKClassDesc is a valid one. Because CK_CLASSID may not be consecutive. */
 		bool Done;
 		// Initialized upon class registration
 		CK_CLASSID Self;
@@ -62,6 +63,7 @@ namespace LibCmo::CK2 {
 		//XContainer::XSArray<CK_CLASSID> ToNotify; // List of ClassID to notify when an object of this class is deleted (inverse of ToBeNotify) 					
 
 		CKClassDesc() :
+			IsValid(false),
 			Done(false),
 			Self(CK_CLASSID::CKCID_OBJECT), Parent(CK_CLASSID::CKCID_OBJECT),
 			CreationFct(nullptr), ReleaseFct(nullptr), NameFct(nullptr),
diff --git a/LibCmo/CK2/CKGlobals.cpp b/LibCmo/CK2/CKGlobals.cpp
index 8dea8b6..70aff57 100644
--- a/LibCmo/CK2/CKGlobals.cpp
+++ b/LibCmo/CK2/CKGlobals.cpp
@@ -11,6 +11,9 @@
 #include <zlib.h>
 
 #include "ObjImpls/CKObject.hpp"
+#include "ObjImpls/CKSceneObject.hpp"
+#include "ObjImpls/CKBeObject.hpp"
+#include "ObjImpls/CKGroup.hpp"
 
 namespace LibCmo::CK2 {
 
@@ -61,17 +64,23 @@ namespace LibCmo::CK2 {
 #pragma region CKClass Registration
 
 	static XContainer::XArray<CKClassDesc> g_CKClassInfo;
-	static std::map<CK_CLASSID, size_t> g_CKClassInfoId2Idx;
-	static CK_CLASSID g_CKClassInfoMaxID = static_cast<CK_CLASSID>(0);
+
+	CK_CLASSID CKClassGetNewIdentifier() {
+		size_t classsize = g_CKClassInfo.size();
+		if (classsize < static_cast<size_t>(CK_CLASSID::CKCID_MAXCLASSID)) {
+			return CK_CLASSID::CKCID_MAXCLASSID;
+		} else {
+			return static_cast<CK_CLASSID>(classsize);
+		}
+	}
 
 	static void ComputeParentsTable(CKClassDesc& desc) {
 		// if it has done, do not process it again.
 		if (desc.Done) return;
 
 		// find direct parent
-		auto finder = g_CKClassInfoId2Idx.find(desc.Parent);
-		if (finder == g_CKClassInfoId2Idx.end()) LIBPANIC("No such CK_CLASSID.");
-		CKClassDesc& parent = g_CKClassInfo[finder->second];
+		CKClassDesc& parent = g_CKClassInfo[static_cast<size_t>(desc.Parent)];
+		if (!parent.IsValid) LIBPANIC("No such CK_CLASSID.");
 
 		// if it is not self inheritance, call recursively
 		if (desc.Self != desc.Parent) {
@@ -81,9 +90,7 @@ namespace LibCmo::CK2 {
 		// copy parent's parents
 		desc.Parents = parent.Parents;
 		// and set self as its parent
-		finder = g_CKClassInfoId2Idx.find(desc.Self);
-		if (finder == g_CKClassInfoId2Idx.end()) LIBPANIC("No such CK_CLASSID.");
-		desc.Parents[finder->second] = true;
+		desc.Parents[static_cast<size_t>(desc.Self)] = true;
 
 		// set derivation level
 		desc.DerivationLevel = parent.DerivationLevel + 1;
@@ -95,26 +102,30 @@ namespace LibCmo::CK2 {
 		// set Done to false and resize all XBitArray
 		size_t classCount = g_CKClassInfo.size();
 		for (auto& item : g_CKClassInfo) {
+			if (!item.IsValid) continue;
+
 			item.Done = false;
 			item.Parents.resize(classCount, false);
 			item.Children.resize(classCount, false);
 		}
 		// compute parents
 		for (auto& item : g_CKClassInfo) {
+			if (!item.IsValid) continue;
+
 			ComputeParentsTable(item);
 		}
 		// compute children by parents table
 		// iterate CKClassDesc::Parents and register it self to gotten parents
 		for (auto& item : g_CKClassInfo) {
-			auto finder = g_CKClassInfoId2Idx.find(item.Self);
-			if (finder == g_CKClassInfoId2Idx.end()) LIBPANIC("No such CK_CLASSID.");
-			size_t selfidx = finder->second;
+			if (!item.IsValid) continue;
 
 			for (size_t idx = 0; idx < classCount; ++idx) {
+				if (!g_CKClassInfo[idx].IsValid) continue;
+
 				// if this idx is its parent,
 				// add self to parent.
 				if (item.Parents[idx]) {
-					g_CKClassInfo[idx].Children[selfidx] = true;
+					g_CKClassInfo[idx].Children[static_cast<size_t>(item.Self)] = true;
 				}
 			}
 		}
@@ -122,54 +133,60 @@ namespace LibCmo::CK2 {
 	void CKClassRegister(CK_CLASSID cid, CK_CLASSID parentCid,
 		CKClassCreationFct createFct, CKClassReleaseFct relFct, CKClassNameFct nameFct) {
 
+		// resize class desc array
+		size_t intcid = static_cast<size_t>(cid);
+		if (intcid >= g_CKClassInfo.size()) {
+			g_CKClassInfo.resize(intcid + 1);
+		}
+
+		// emplace desc
 		CKClassDesc desc;
+		desc.IsValid = true;
 		desc.Self = cid;
 		desc.Parent = parentCid;
 		desc.CreationFct = createFct;
 		desc.ReleaseFct = relFct;
 		desc.NameFct = nameFct;
-		g_CKClassInfoId2Idx.emplace(cid, g_CKClassInfo.size());
-		g_CKClassInfo.emplace_back(std::move(desc));
-		g_CKClassInfoMaxID = std::max(g_CKClassInfoMaxID, cid);
+		g_CKClassInfo[intcid] = std::move(desc);
 	}
 
 #pragma endregion
 
 #pragma region Class Hierarchy Management
 
-	CKINT CKGetClassCount() {
-		return static_cast<CKINT>(g_CKClassInfo.size());
+	static bool GetClassIdIndex(CK_CLASSID cid, size_t& intcid) {
+		intcid = static_cast<size_t>(cid);
+		if (intcid >= g_CKClassInfo.size()) return false;
+		if (!g_CKClassInfo[intcid].IsValid) return false;
+		return true;
+	}
+
+	CKDWORD CKGetClassCount() {
+		return static_cast<CKDWORD>(g_CKClassInfo.size());
 	}
 
 	const CKClassDesc* CKGetClassDesc(CK_CLASSID cid) {
-		auto finder = g_CKClassInfoId2Idx.find(cid);
-		if (finder == g_CKClassInfoId2Idx.end()) return nullptr;
-		return g_CKClassInfo.data() + finder->second;
+		size_t intcid;
+		if (!GetClassIdIndex(cid, intcid)) return nullptr;
+		return &g_CKClassInfo[intcid];
 	}
 
 	CKSTRING CKClassIDToString(CK_CLASSID cid) {
-		auto finder = g_CKClassInfoId2Idx.find(cid);
-		if (finder == g_CKClassInfoId2Idx.end() || g_CKClassInfo[finder->second].NameFct == nullptr) return "Invalid Class Identifier";
-		return g_CKClassInfo[finder->second].NameFct();
+		const CKClassDesc* desc = CKGetClassDesc(cid);
+		if (desc == nullptr) return "Undefined Type";
+		else return desc->NameFct();
 	}
 
 	bool CKIsChildClassOf(CK_CLASSID child, CK_CLASSID parent) {
-		// get corresponding index first
-		// if we can't find it, return false anyway.
-		auto finder = g_CKClassInfoId2Idx.find(child);
-		if (finder == g_CKClassInfoId2Idx.end()) return false;
-		size_t child_idx = finder->second;
-		finder = g_CKClassInfoId2Idx.find(parent);
-		if (finder == g_CKClassInfoId2Idx.end()) return false;
-		size_t parent_idx = finder->second;
-
-		return g_CKClassInfo[child_idx].Parents[parent_idx];
+		size_t intchild, intparent;
+		if (!GetClassIdIndex(child, intchild) || !GetClassIdIndex(parent, intparent)) return false;
+		return g_CKClassInfo[intchild].Parents[intparent];
 	}
 
 	CK_CLASSID CKGetParentClassID(CK_CLASSID child) {
-		auto finder = g_CKClassInfoId2Idx.find(child);
-		if (finder == g_CKClassInfoId2Idx.end()) LIBPANIC("No such CK_CLASSID.");
-		return g_CKClassInfo[finder->second].Parent;
+		const CKClassDesc* desc = CKGetClassDesc(child);
+		if (desc == nullptr) return CK_CLASSID::CKCID_OBJECT;
+		return desc->Parent;
 	}
 
 	CK_CLASSID CKGetCommonParent(CK_CLASSID cid1, CK_CLASSID cid2) {
@@ -190,11 +207,28 @@ namespace LibCmo::CK2 {
 #pragma region Initializations functions
 
 	CKERROR CKStartUp() {
+
+		// reserve class info array.
+		g_CKClassInfo.reserve(static_cast<size_t>(CK_CLASSID::CKCID_MAXCLASSID));
+
 		// todo: add class type registrations
-		CKClassRegister(CK_CLASSID::CKCID_OBJECT, CK_CLASSID::CKCID_OBJECT,
-			[](CKContext* ctx, CK_ID id, CKSTRING name) -> ObjImpls::CKObject* { return new ObjImpls::CKObject(ctx, id, name); },
-			[](CKContext* ctx, ObjImpls::CKObject* obj) -> void { delete obj; },
-			[]() -> CKSTRING { return "Basic Object"; });
+#define EasyClassReg(clsname, cid, parentCid, strName) \
+CKClassRegister(cid, parentCid, \
+	[](CKContext* ctx, CK_ID id, CKSTRING name) -> ObjImpls::CKObject* { return new clsname(ctx, id, name); }, \
+	[](CKContext* ctx, ObjImpls::CKObject* obj) -> void { delete obj; }, \
+	[]() -> CKSTRING { return strName; });
+
+		EasyClassReg(ObjImpls::CKObject, CK_CLASSID::CKCID_OBJECT, CK_CLASSID::CKCID_OBJECT, "Basic Object");
+		EasyClassReg(ObjImpls::CKSceneObject, CK_CLASSID::CKCID_SCENEOBJECT, CK_CLASSID::CKCID_OBJECT, "Scene Object");
+		EasyClassReg(ObjImpls::CKBeObject, CK_CLASSID::CKCID_BEOBJECT, CK_CLASSID::CKCID_SCENEOBJECT, "Behavioral Object");
+		EasyClassReg(ObjImpls::CKGroup, CK_CLASSID::CKCID_GROUP, CK_CLASSID::CKCID_BEOBJECT, "Group");
+
+		//CKClassRegister(CK_CLASSID::CKCID_OBJECT, CK_CLASSID::CKCID_OBJECT,
+		//	[](CKContext* ctx, CK_ID id, CKSTRING name) -> ObjImpls::CKObject* { return new ObjImpls::CKObject(ctx, id, name); },
+		//	[](CKContext* ctx, ObjImpls::CKObject* obj) -> void { delete obj; },
+		//	[]() -> CKSTRING { return "Basic Object"; });
+
+#undef EasyClassReg
 
 		/*
 				// register CKObjects
@@ -233,8 +267,6 @@ namespace LibCmo::CK2 {
 	CKERROR CKShutdown() {
 		// free class indo
 		g_CKClassInfo.clear();
-		g_CKClassInfoId2Idx.clear();
-		g_CKClassInfoMaxID = static_cast<CK_CLASSID>(0);
 
 		return CKERROR::CKERR_OK;
 	}
diff --git a/LibCmo/CK2/CKGlobals.hpp b/LibCmo/CK2/CKGlobals.hpp
index 53b3c49..cac3f72 100644
--- a/LibCmo/CK2/CKGlobals.hpp
+++ b/LibCmo/CK2/CKGlobals.hpp
@@ -54,12 +54,13 @@ namespace LibCmo::CK2 {
 
 	// ========== CKClass Registration ==========
 
+	CK_CLASSID CKClassGetNewIdentifier();
 	void CKClassRegister(CK_CLASSID cid, CK_CLASSID parentCid,
 		CKClassCreationFct createFct, CKClassReleaseFct relFct, CKClassNameFct nameFct);
 
 	// ========== Class Hierarchy Management ==========
 
-	CKINT CKGetClassCount();
+	CKDWORD CKGetClassCount();
 	const CKClassDesc* CKGetClassDesc(CK_CLASSID cid);
 	CKSTRING CKClassIDToString(CK_CLASSID cid);
 
diff --git a/LibCmo/CK2/ObjImpls/CKBeObject.cpp b/LibCmo/CK2/ObjImpls/CKBeObject.cpp
index 032fb77..6a664b6 100644
--- a/LibCmo/CK2/ObjImpls/CKBeObject.cpp
+++ b/LibCmo/CK2/ObjImpls/CKBeObject.cpp
@@ -22,4 +22,9 @@ namespace LibCmo::CK2::ObjImpls {
 		return false;
 	}
 
+	void CKBeObject::CKGroup_SetGroups(CKDWORD pos, bool val) {
+		if (pos >= m_Groups.size()) m_Groups.resize(pos + 1);
+		m_Groups[pos] = val;
+	}
+
 }
\ No newline at end of file
diff --git a/LibCmo/CK2/ObjImpls/CKBeObject.hpp b/LibCmo/CK2/ObjImpls/CKBeObject.hpp
index e6129b8..a21e1a2 100644
--- a/LibCmo/CK2/ObjImpls/CKBeObject.hpp
+++ b/LibCmo/CK2/ObjImpls/CKBeObject.hpp
@@ -22,6 +22,7 @@ namespace LibCmo::CK2::ObjImpls {
 		//virtual void PostLoad() override;
 
 		bool IsInGroup(CKGroup* group);
+		void CKGroup_SetGroups(CKDWORD pos, bool val);
 		
 	protected:
 		XContainer::XBitArray m_Groups;
diff --git a/LibCmo/CK2/ObjImpls/CKGroup.cpp b/LibCmo/CK2/ObjImpls/CKGroup.cpp
index f95f27c..b5920ab 100644
--- a/LibCmo/CK2/ObjImpls/CKGroup.cpp
+++ b/LibCmo/CK2/ObjImpls/CKGroup.cpp
@@ -1,27 +1,92 @@
-#include "CKSceneObject.hpp"
-#include "../CKStateChunk.hpp"
 #include "CKGroup.hpp"
+#include "../CKStateChunk.hpp"
+#include "../CKContext.hpp"
+#include <algorithm>
 
 namespace LibCmo::CK2::ObjImpls {
 
+	CKGroup::CKGroup(CKContext* ctx, CK_ID ckid, CKSTRING name) :
+		CKBeObject(ctx, ckid, name),
+		m_ObjectArray(),
+		m_GroupIndex(m_Context->AllocateGroupGlobalIndex()) {}
+
+	CKGroup::~CKGroup() {
+		m_Context->FreeGroupGlobalIndex(m_GroupIndex);
+	}
+
 	bool CKGroup::Save(CKStateChunk* chunk, CKFileVisitor* file, CKDWORD flags) {
-		return false;
+		bool suc = CKBeObject::Save(chunk, file, flags);
+		if (!suc) return false;
+
+		return true;
 	}
 
 	bool CKGroup::Load(CKStateChunk* chunk, CKFileVisitor* file) {
-		return false;
+		bool suc = CKBeObject::Load(chunk, file);
+		if (!suc) return false;
+
+		return true;
 	}
 
 	CKDWORD CKGroup::GetGroupIndex() {
 		return m_GroupIndex;
 	}
 
-	CKObject* CKGroup::GetObject(CKDWORD pos) {
-		return nullptr;
+	CKERROR CKGroup::AddObject(CKBeObject* o) {
+		if (o == nullptr || o == this || !CKIsChildClassOf(o->GetClassID(), CK_CLASSID::CKCID_BEOBJECT)) {
+			return CKERROR::CKERR_INVALIDPARAMETER;
+		}
+		if (o->IsInGroup(this)) {
+			return CKERROR::CKERR_ALREADYPRESENT;
+		}
+
+		// set object
+		o->CKGroup_SetGroups(m_GroupIndex, true);
+		// set self
+		m_ObjectArray.emplace_back(o);
+		return CKERROR::CKERR_OK;
+	}
+
+	CKBeObject* CKGroup::RemoveObject(CKDWORD pos) {
+		// check pos
+		if (pos >= m_ObjectArray.size()) return nullptr;
+
+		auto it = m_ObjectArray.begin() + pos;
+		CKBeObject* obj = static_cast<CKBeObject*>(*it);
+		// set object
+		obj->CKGroup_SetGroups(m_GroupIndex, false);
+		// remove self
+		m_ObjectArray.erase(it);
+		return obj;
+	}
+
+	void CKGroup::RemoveObject(CKBeObject* obj) {
+		// find first
+		auto finder = std::find(m_ObjectArray.begin(), m_ObjectArray.end(), static_cast<CKObject*>(obj));
+		if (finder != m_ObjectArray.end()) {
+			// set object
+			static_cast<CKBeObject*>(*finder)->CKGroup_SetGroups(m_GroupIndex, false);
+			// remove self
+			m_ObjectArray.erase(finder);
+		}
+	}
+
+	void CKGroup::Clear() {
+		for (auto& beobj : m_ObjectArray) {
+			// set object
+			static_cast<CKBeObject*>(beobj)->CKGroup_SetGroups(m_GroupIndex, false);
+		}
+
+		m_ObjectArray.clear();
+	}
+
+	CKBeObject* CKGroup::GetObject(CKDWORD pos) {
+		if (pos >= m_ObjectArray.size()) return nullptr;
+		else return static_cast<CKBeObject*>(m_ObjectArray[pos]);
 	}
 
 	CKDWORD CKGroup::GetObjectCount() {
-		return CKDWORD();
+		return static_cast<CKDWORD>(m_ObjectArray.size());
 	}
 
 }
diff --git a/LibCmo/CK2/ObjImpls/CKGroup.hpp b/LibCmo/CK2/ObjImpls/CKGroup.hpp
index 97c50ae..7a3531a 100644
--- a/LibCmo/CK2/ObjImpls/CKGroup.hpp
+++ b/LibCmo/CK2/ObjImpls/CKGroup.hpp
@@ -7,14 +7,8 @@ namespace LibCmo::CK2::ObjImpls {
 
 	class CKGroup : public CKBeObject {
 	public:
-		CKGroup(CKContext* ctx, CK_ID ckid, CKSTRING name) : 
-			CKBeObject(ctx, ckid, name),
-			m_ObjectArray(),
-			m_GroupIndex()	// todo: allocate group id
-		{}
-		virtual ~CKGroup() {
-			// todo: free allocated group id
-		}
+		CKGroup(CKContext* ctx, CK_ID ckid, CKSTRING name);
+		virtual ~CKGroup();
 		LIBCMO_DISABLE_COPY_MOVE(CKGroup);
 		
 		virtual CK_CLASSID GetClassID(void) override { 
@@ -29,20 +23,14 @@ namespace LibCmo::CK2::ObjImpls {
 		
 		// ===== Insert =====
 		CKERROR AddObject(CKBeObject *o);
-		CKERROR AddObjectFront(CKBeObject *o);
-		CKERROR InsertObjectAt(CKBeObject *o, CKDWORD pos);
 		
 		// ===== Remove =====
 		CKBeObject* RemoveObject(CKDWORD pos);
 		void RemoveObject(CKBeObject *obj);
 		void Clear();
 		
-		// ===== Order =====
-		void MoveObjectUp(CKBeObject *o);
-		void MoveObjectDown(CKBeObject *o);
-		
 		// ===== Access =====
-		CKObject* GetObject(CKDWORD pos);
+		CKBeObject* GetObject(CKDWORD pos);
 		CKDWORD GetObjectCount();
 
 	protected:
diff --git a/LibCmo/LibCmo.vcxproj b/LibCmo/LibCmo.vcxproj
index b9f9b18..55c3b31 100644
--- a/LibCmo/LibCmo.vcxproj
+++ b/LibCmo/LibCmo.vcxproj
@@ -189,6 +189,7 @@
     <ClCompile Include="CK2\CKStateChunk.cpp" />
     <ClCompile Include="VTUtils.cpp" />
     <ClCompile Include="VxMath\VxMemoryMappedFile.cpp" />
+    <ClCompile Include="XContainer\XBitArray.cpp" />
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="CK2\CKDefines.hpp" />
@@ -209,6 +210,7 @@
     <ClInclude Include="VTUtils.hpp" />
     <ClInclude Include="VxMath\VxMemoryMappedFile.hpp" />
     <ClInclude Include="VxMath\VxTypes.hpp" />
+    <ClInclude Include="XContainer\XBitArray.hpp" />
     <ClInclude Include="XContainer\XTypes.hpp" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
diff --git a/LibCmo/LibCmo.vcxproj.filters b/LibCmo/LibCmo.vcxproj.filters
index cad2ac9..d3245bc 100644
--- a/LibCmo/LibCmo.vcxproj.filters
+++ b/LibCmo/LibCmo.vcxproj.filters
@@ -87,6 +87,9 @@
     <ClCompile Include="CK2\ObjImpls\CKGroup.cpp">
       <Filter>Sources\CK2\ObjImpls</Filter>
     </ClCompile>
+    <ClCompile Include="XContainer\XBitArray.cpp">
+      <Filter>Sources\XContainer</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="VTUtils.hpp">
@@ -146,5 +149,8 @@
     <ClInclude Include="CK2\ObjImpls\CKGroup.hpp">
       <Filter>Headers\CK2\ObjImpls</Filter>
     </ClInclude>
+    <ClInclude Include="XContainer\XBitArray.hpp">
+      <Filter>Headers\XContainer</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/LibCmo/XContainer/XBitArray.cpp b/LibCmo/XContainer/XBitArray.cpp
new file mode 100644
index 0000000..679bb28
--- /dev/null
+++ b/LibCmo/XContainer/XBitArray.cpp
@@ -0,0 +1,30 @@
+#include "XBitArray.hpp"
+
+namespace LibCmo::XContainer::XBitArrayPatch {
+
+	template<bool _Cond>
+	bool GeneralGetBitPosition(XBitArray& ba, CK2::CKDWORD n, CK2::CKDWORD& got) {
+		CK2::CKDWORD counter = 0;
+		for (size_t i = 0; i < ba.size(); ++i) {
+			if (ba[i] == _Cond) {
+				if (counter == n) {
+					got = static_cast<CK2::CKDWORD>(i);
+					return true;
+				} else {
+					++counter;
+				}
+			}
+		}
+
+		return false;
+	}
+
+	bool GetSetBitPosition(XBitArray& ba, CK2::CKDWORD n, CK2::CKDWORD& got) {
+		return GeneralGetBitPosition<true>(ba, n, got);
+	}
+
+	bool GetUnsetBitPosition(XBitArray& ba, CK2::CKDWORD n, CK2::CKDWORD& got) {
+		return GeneralGetBitPosition<false>(ba, n, got);
+	}
+
+}
diff --git a/LibCmo/XContainer/XBitArray.hpp b/LibCmo/XContainer/XBitArray.hpp
new file mode 100644
index 0000000..988aa7b
--- /dev/null
+++ b/LibCmo/XContainer/XBitArray.hpp
@@ -0,0 +1,17 @@
+#pragma once
+#include "XTypes.hpp"
+
+namespace LibCmo::XContainer::XBitArrayPatch {
+
+	/**
+	 * @brief Returns the position of the n-th set(1) bit
+	 * @return false if not found.
+	*/
+	bool GetSetBitPosition(XBitArray& ba, CK2::CKDWORD n, CK2::CKDWORD& got);
+	/**
+	 * @brief Returns the position of the n-th unset(0) bit
+	 * @return false if not found.
+	*/
+	bool GetUnsetBitPosition(XBitArray& ba, CK2::CKDWORD n, CK2::CKDWORD& got);
+
+}
diff --git a/Unvirt/StructFormatter.cpp b/Unvirt/StructFormatter.cpp
index 8df3cd0..9a6d7df 100644
--- a/Unvirt/StructFormatter.cpp
+++ b/Unvirt/StructFormatter.cpp
@@ -167,14 +167,28 @@ namespace Unvirt::StructFormatter {
 
 	void PrintCKObject(const LibCmo::CK2::ObjImpls::CKObject* obj) {
 		fputs(UNVIRT_TERMCOL_LIGHT_YELLOW(("CKObject\n")), stdout);
+		if (obj == nullptr) {
+			fputs(UNVIRT_TERMCOL_LIGHT_RED(("No Data\n")), stdout);
+			return;
+		}
+
 		fputs(UNVIRT_TERMCOL_LIGHT_RED(("Not Implemented.\n")), stdout);
 	}
 	void PrintCKBaseManager(const LibCmo::CK2::MgrImpls::CKBaseManager* mgr) {
 		fputs(UNVIRT_TERMCOL_LIGHT_YELLOW(("CKBaseManager\n")), stdout);
+		if (mgr == nullptr) {
+			fputs(UNVIRT_TERMCOL_LIGHT_RED(("No Data\n")), stdout);
+			return;
+		}
+
 		fputs(UNVIRT_TERMCOL_LIGHT_RED(("Not Implemented.\n")), stdout);
 	}
 	void PrintCKStateChunk(const LibCmo::CK2::CKStateChunk* chunk) {
 		fputs(UNVIRT_TERMCOL_LIGHT_YELLOW(("CKStateChunk\n")), stdout);
+		if (chunk == nullptr) {
+			fputs(UNVIRT_TERMCOL_LIGHT_RED(("No Data\n")), stdout);
+			return;
+		}
 
 		// hack const state chunk
 		LibCmo::CK2::CKStateChunk* operchunk = const_cast<LibCmo::CK2::CKStateChunk*>(chunk);
diff --git a/Unvirt/UnvirtContext.cpp b/Unvirt/UnvirtContext.cpp
index 1cc31c9..cbc7d50 100644
--- a/Unvirt/UnvirtContext.cpp
+++ b/Unvirt/UnvirtContext.cpp
@@ -127,6 +127,7 @@ namespace Unvirt::Context {
 		m_Help = root->RootHelp();
 
 		// create context
+		LibCmo::CK2::CKStartUp();
 		m_Ctx = new LibCmo::CK2::CKContext();
 		m_Ctx->SetOutputCallback(std::bind(&UnvirtContext::PrintContextMsg, this, std::placeholders::_1));
 	}
@@ -134,6 +135,11 @@ namespace Unvirt::Context {
 	UnvirtContext::~UnvirtContext() {
 		if (m_Help != nullptr)
 			delete m_Help;
+
+		// free context
+		ClearDocument();
+		delete m_Ctx;
+		LibCmo::CK2::CKShutdown();
 	}
 
 	bool UnvirtContext::HasOpenedFile() {