diff --git a/src/mapblock_nodemod.h b/src/mapblock_nodemod.h
new file mode 100644
index 0000000..4952df1
--- /dev/null
+++ b/src/mapblock_nodemod.h
@@ -0,0 +1,114 @@
+/*
+Minetest-c55
+Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef MAPBLOCK_NODEMOD_HEADER
+#define MAPBLOCK_NODEMOD_HEADER
+
+enum NodeModType
+{
+	NODEMOD_NONE,
+	NODEMOD_CHANGECONTENT, //param is content id
+	NODEMOD_CRACK // param is crack progression
+};
+
+struct NodeMod
+{
+	NodeMod(enum NodeModType a_type=NODEMOD_NONE, u16 a_param=0)
+	{
+		type = a_type;
+		param = a_param;
+	}
+	bool operator==(const NodeMod &other)
+	{
+		return (type == other.type && param == other.param);
+	}
+	enum NodeModType type;
+	u16 param;
+};
+
+class NodeModMap
+{
+public:
+	/*
+		returns true if the mod was different last time
+	*/
+	bool set(v3s16 p, const NodeMod &mod)
+	{
+		// See if old is different, cancel if it is not different.
+		core::map<v3s16, NodeMod>::Node *n = m_mods.find(p);
+		if(n)
+		{
+			NodeMod old = n->getValue();
+			if(old == mod)
+				return false;
+
+			n->setValue(mod);
+		}
+		else
+		{
+			m_mods.insert(p, mod);
+		}
+		
+		return true;
+	}
+	// Returns true if there was one
+	bool get(v3s16 p, NodeMod *mod)
+	{
+		core::map<v3s16, NodeMod>::Node *n;
+		n = m_mods.find(p);
+		if(n == NULL)
+			return false;
+		if(mod)
+			*mod = n->getValue();
+		return true;
+	}
+	bool clear(v3s16 p)
+	{
+		if(m_mods.find(p))
+		{
+			m_mods.remove(p);
+			return true;
+		}
+		return false;
+	}
+	bool clear()
+	{
+		if(m_mods.size() == 0)
+			return false;
+		m_mods.clear();
+		return true;
+	}
+	void copy(NodeModMap &dest)
+	{
+		dest.m_mods.clear();
+
+		for(core::map<v3s16, NodeMod>::Iterator
+				i = m_mods.getIterator();
+				i.atEnd() == false; i++)
+		{
+			dest.m_mods.insert(i.getNode()->getKey(), i.getNode()->getValue());
+		}
+	}
+
+private:
+	core::map<v3s16, NodeMod> m_mods;
+};
+
+#endif
+