diff --git a/src/SerializedObject.cpp b/src/SerializedObject.cpp
index e27ce55d28..c09e67904d 100644
--- a/src/SerializedObject.cpp
+++ b/src/SerializedObject.cpp
@@ -167,6 +167,22 @@ std::string STObject::getText() const
 	return ret;
 }
 
+bool STObject::isEquivalent(const SerializedType& t) const
+{
+	const STObject* v=dynamic_cast<const STObject*>(&t);
+	if(!v) return false;
+	boost::ptr_vector<SerializedType>::const_iterator it1=mData.begin(), end1=mData.end();
+	boost::ptr_vector<SerializedType>::const_iterator it2=v->mData.begin(), end2=v->mData.end();
+	while((it1!=end1) && (it2!=end2))
+	{
+		if(it1->getType() != it2->getType()) return false;
+		if(!it1->isEquivalent(*it2)) return false;
+		++it1;
+		++it2;
+	}
+	return (it1==end1) && (it2==end2);
+}
+
 int STObject::getFieldIndex(SOE_Field field) const
 {
 	int i=0;
diff --git a/src/SerializedObject.h b/src/SerializedObject.h
index f1e53ad141..16dc182858 100644
--- a/src/SerializedObject.h
+++ b/src/SerializedObject.h
@@ -58,6 +58,7 @@ public:
 	int getLength() const;
 	SerializedTypeID getType() const { return STI_OBJECT; }
 	STObject* duplicate() const { return new STObject(*this); }
+	virtual bool isEquivalent(const SerializedType& t) const;
 
 	void add(Serializer& s) const;
 	std::string getFullText() const;
diff --git a/src/SerializedTransaction.cpp b/src/SerializedTransaction.cpp
index 8192a8e71b..88dd761c32 100644
--- a/src/SerializedTransaction.cpp
+++ b/src/SerializedTransaction.cpp
@@ -77,6 +77,16 @@ int SerializedTransaction::getTransaction(Serializer& s, bool include_length) co
 	return l;
 }
 
+bool SerializedTransaction::isEquivalent(const SerializedType& t) const
+{ // Signatures are not compared
+	const SerializedTransaction* v=dynamic_cast<const SerializedTransaction*>(&t);
+	if(!v) return false;
+	if(type != v->type) return false;
+	if(mMiddleTxn != v->mMiddleTxn) return false;
+	if(mInnerTxn != v->mInnerTxn) return false;
+	return true;
+}
+
 uint256 SerializedTransaction::getSigningHash() const
 {
 	Serializer s;
diff --git a/src/SerializedTransaction.h b/src/SerializedTransaction.h
index 644634d8f6..3f64589549 100644
--- a/src/SerializedTransaction.h
+++ b/src/SerializedTransaction.h
@@ -31,6 +31,7 @@ public:
 	std::string getFullText() const;
 	std::string getText() const;
 	void add(Serializer& s) const { getTransaction(s, true); }
+	virtual bool isEquivalent(const SerializedType& t) const;
 
 	// outer transaction functions / signature functions
 	std::vector<unsigned char> getSignature() const;
diff --git a/src/SerializedTypes.cpp b/src/SerializedTypes.cpp
index 80d63de302..a7527b332e 100644
--- a/src/SerializedTypes.cpp
+++ b/src/SerializedTypes.cpp
@@ -31,6 +31,12 @@ std::string STUInt8::getText() const
 	return boost::lexical_cast<std::string>(value);
 }
 
+bool STUInt8::isEquivalent(const SerializedType& t) const
+{
+	const STUInt8* v=dynamic_cast<const STUInt8*>(&t);
+	return v && (value==v->value);
+}
+
 STUInt16* STUInt16::construct(SerializerIterator& u, const char *name)
 {
 	return new STUInt16(name, u.get16());
@@ -41,8 +47,14 @@ std::string STUInt16::getText() const
 	return boost::lexical_cast<std::string>(value);
 }
 
-STUInt32* STUInt32::construct(SerializerIterator& u, const char *name)
+bool STUInt16::isEquivalent(const SerializedType& t) const
 {
+	const STUInt16* v=dynamic_cast<const STUInt16*>(&t);
+	return v && (value==v->value);
+}
+
+STUInt32* STUInt32::construct(SerializerIterator& u, const char *name)
+ {
 	return new STUInt32(name, u.get32());
 }
 
@@ -51,6 +63,12 @@ std::string STUInt32::getText() const
 	return boost::lexical_cast<std::string>(value);
 }
 
+bool STUInt32::isEquivalent(const SerializedType& t) const
+{
+	const STUInt32* v=dynamic_cast<const STUInt32*>(&t);
+	return v && (value==v->value);
+}
+
 STUInt64* STUInt64::construct(SerializerIterator& u, const char *name)
 {
 	return new STUInt64(name, u.get64());
@@ -61,6 +79,12 @@ std::string STUInt64::getText() const
 	return boost::lexical_cast<std::string>(value);
 }
 
+bool STUInt64::isEquivalent(const SerializedType& t) const
+{
+	const STUInt64* v=dynamic_cast<const STUInt64*>(&t);
+	return v && (value==v->value);
+}
+
 STHash128* STHash128::construct(SerializerIterator& u, const char *name)
 {
 	return new STHash128(name, u.get128());
@@ -71,6 +95,12 @@ std::string STHash128::getText() const
 	return value.GetHex();
 }
 
+bool STHash128::isEquivalent(const SerializedType& t) const
+{
+	const STHash128* v=dynamic_cast<const STHash128*>(&t);
+	return v && (value==v->value);
+}
+
 STHash160* STHash160::construct(SerializerIterator& u, const char *name)
 {
 	return new STHash160(name, u.get160());
@@ -81,6 +111,12 @@ std::string STHash160::getText() const
 	return value.GetHex();
 }
 
+bool STHash160::isEquivalent(const SerializedType& t) const
+{
+	const STHash160* v=dynamic_cast<const STHash160*>(&t);
+	return v && (value==v->value);
+}
+
 STHash256* STHash256::construct(SerializerIterator& u, const char *name)
 {
 	return new STHash256(name, u.get256());
@@ -91,6 +127,12 @@ std::string STHash256::getText() const
 	return value.GetHex();
 }
 
+bool STHash256::isEquivalent(const SerializedType& t) const
+{
+	const STHash256* v=dynamic_cast<const STHash256*>(&t);
+	return v && (value==v->value);
+}
+
 static std::string hex(const std::vector<unsigned char>& value)
 {
 	int dlen=value.size(), i=0;
@@ -115,6 +157,12 @@ int STVariableLength::getLength() const
 	return Serializer::encodeLengthLength(value.size()) + value.size();
 }
 
+bool STVariableLength::isEquivalent(const SerializedType& t) const
+{
+	const STVariableLength* v=dynamic_cast<const STVariableLength*>(&t);
+	return v && (value==v->value);
+}
+
 std::string STAccount::getText() const
 {
 	uint160 u;
@@ -177,4 +225,8 @@ int STTaggedList::getLength() const
 	return ret;
 }
 
-
+bool STTaggedList::isEquivalent(const SerializedType& t) const
+{
+	const STTaggedList* v=dynamic_cast<const STTaggedList*>(&t);
+	return v && (value==v->value);
+}
diff --git a/src/SerializedTypes.h b/src/SerializedTypes.h
index 53b1375c68..3c43e1aadd 100644
--- a/src/SerializedTypes.h
+++ b/src/SerializedTypes.h
@@ -46,6 +46,13 @@ public:
 
 	SerializedType* new_clone(const SerializedType& s) { return s.duplicate(); }
 	void delete_clone(const SerializedType* s) { boost::checked_delete(s); }
+
+	virtual bool isEquivalent(const SerializedType& t) const { return true; }
+
+	bool operator==(const SerializedType& t) const
+	{ return (getType()==t.getType()) && isEquivalent(t); }
+	bool operator!=(const SerializedType& t) const
+	{ return (getType()!=t.getType()) || !isEquivalent(t); }
 };
 
 class STUInt8 : public SerializedType
@@ -70,6 +77,7 @@ public:
 
 	operator unsigned char() const { return value; }
 	STUInt8& operator=(unsigned char v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 class STUInt16 : public SerializedType
@@ -94,6 +102,7 @@ public:
 
 	operator uint16() const { return value; }
 	STUInt16& operator=(uint16 v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 class STUInt32 : public SerializedType
@@ -118,6 +127,7 @@ public:
 
 	operator uint32() const { return value; }
 	STUInt32& operator=(uint32 v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 class STUInt64 : public SerializedType
@@ -142,6 +152,7 @@ public:
 
 	operator uint64() const { return value; }
 	STUInt64& operator=(uint64 v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 class STHash128 : public SerializedType
@@ -167,6 +178,7 @@ public:
 
 	operator uint128() const { return value; }
 	STHash128& operator=(const uint128& v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 class STHash160 : public SerializedType
@@ -192,6 +204,7 @@ public:
 
 	operator uint160() const { return value; }
 	STHash160& operator=(const uint160& v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 class STHash256 : public SerializedType
@@ -217,6 +230,7 @@ public:
 
 	operator uint256() const { return value; }
 	STHash256& operator=(const uint256& v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 class STVariableLength : public SerializedType
@@ -245,6 +259,7 @@ public:
 
 	operator std::vector<unsigned char>() const { return value; }
 	STVariableLength& operator=(const std::vector<unsigned char>& v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 class STAccount : public STVariableLength
@@ -299,6 +314,7 @@ public:
 
 	operator std::vector<TaggedListItem>() const { return value; }
 	STTaggedList& operator=(const std::vector<TaggedListItem>& v) { value=v; return *this; }
+	virtual bool isEquivalent(const SerializedType& t) const;
 };
 
 #endif