diff --git a/apps/opencs/CMakeLists.txt b/apps/opencs/CMakeLists.txt
index 9f33c862a..8e0024ad9 100644
--- a/apps/opencs/CMakeLists.txt
+++ b/apps/opencs/CMakeLists.txt
@@ -107,6 +107,10 @@ opencs_units_noqt (model/settings
     settingsitem
     )
 
+opencs_units_noqt (model/filter
+    node unarynode binarynode leafnode booleannode
+    )
+
 opencs_hdrs_noqt (model/filter
     filter
     )
diff --git a/apps/opencs/model/filter/binarynode.cpp b/apps/opencs/model/filter/binarynode.cpp
new file mode 100644
index 000000000..0e86930db
--- /dev/null
+++ b/apps/opencs/model/filter/binarynode.cpp
@@ -0,0 +1,58 @@
+
+#include "binarynode.hpp"
+
+CSMFilter::BinaryNode::BinaryNode (std::auto_ptr<Node> left, std::auto_ptr<Node> right)
+: mLeft (left), mRight (right)
+{}
+
+const CSMFilter::Node& CSMFilter::BinaryNode::getLeft() const
+{
+    return *mLeft;
+}
+
+CSMFilter::Node& CSMFilter::BinaryNode::getLeft()
+{
+    return *mLeft;
+}
+
+const CSMFilter::Node& CSMFilter::BinaryNode::getRight() const
+{
+    return *mRight;
+}
+
+CSMFilter::Node& CSMFilter::BinaryNode::getRight()
+{
+    return *mRight;
+}
+
+std::vector<std::string> CSMFilter::BinaryNode::getReferencedFilters() const
+{
+    std::vector<std::string> left = mLeft->getReferencedFilters();
+
+    std::vector<std::string> right = mRight->getReferencedFilters();
+
+    left.insert (left.end(), right.begin(), right.end());
+
+    return left;
+}
+
+std::vector<int> CSMFilter::BinaryNode::getReferencedColumns() const
+{
+    std::vector<int> left = mLeft->getReferencedColumns();
+
+    std::vector<int> right = mRight->getReferencedColumns();
+
+    left.insert (left.end(), right.begin(), right.end());
+
+    return left;
+}
+
+bool CSMFilter::BinaryNode::isSimple() const
+{
+    return false;
+}
+
+bool CSMFilter::BinaryNode::hasUserValue() const
+{
+    return mLeft->hasUserValue() || mRight->hasUserValue();
+}
diff --git a/apps/opencs/model/filter/binarynode.hpp b/apps/opencs/model/filter/binarynode.hpp
new file mode 100644
index 000000000..18cdad2a9
--- /dev/null
+++ b/apps/opencs/model/filter/binarynode.hpp
@@ -0,0 +1,42 @@
+#ifndef CSM_FILTER_BINARYNODE_H
+#define CSM_FILTER_BINARYNODE_H
+
+#include <memory>
+
+#include "node.hpp"
+
+namespace CSMFilter
+{
+    class BinaryNode : public Node
+    {
+            std::auto_ptr<Node> mLeft;
+            std::auto_ptr<Node> mRight;
+
+        public:
+
+            BinaryNode (std::auto_ptr<Node> left, std::auto_ptr<Node> right);
+
+            const Node& getLeft() const;
+
+            Node& getLeft();
+
+            const Node& getRight() const;
+
+            Node& getRight();
+
+            virtual std::vector<std::string> getReferencedFilters() const;
+            ///< Return a list of filters that are used by this node (and must be passed as
+            /// otherFilters when calling test).
+
+            virtual std::vector<int> getReferencedColumns() const;
+            ///< Return a list of the IDs of the columns referenced by this node. The column mapping
+            /// passed into test as columns must contain all columns listed here.
+
+            virtual bool isSimple() const;
+            ///< \return Can this filter be displayed in simple mode.
+
+            virtual bool hasUserValue() const;
+    };
+}
+
+#endif
diff --git a/apps/opencs/model/filter/booleannode.cpp b/apps/opencs/model/filter/booleannode.cpp
new file mode 100644
index 000000000..cea130d24
--- /dev/null
+++ b/apps/opencs/model/filter/booleannode.cpp
@@ -0,0 +1,17 @@
+
+#include "booleannode.hpp"
+
+CSMFilter::BooleanNode::BooleanNode (bool true_) : mTrue (true) {}
+
+bool CSMFilter::BooleanNode::test (const CSMWorld::IdTable& table, int row,
+    const std::map<std::string, const Node *>& otherFilters,
+    const std::map<int, int>& columns,
+    const std::string& userValue) const
+{
+    return mTrue;
+}
+
+std::string CSMFilter::BooleanNode::toString (bool numericColumns) const
+{
+    return mTrue ? "true" : "false";
+}
\ No newline at end of file
diff --git a/apps/opencs/model/filter/booleannode.hpp b/apps/opencs/model/filter/booleannode.hpp
new file mode 100644
index 000000000..3578c7f3f
--- /dev/null
+++ b/apps/opencs/model/filter/booleannode.hpp
@@ -0,0 +1,31 @@
+#ifndef CSM_FILTER_BOOLEANNODE_H
+#define CSM_FILTER_BOOLEANNODE_H
+
+#include "leafnode.hpp"
+
+namespace CSMFilter
+{
+    class BooleanNode : public LeafNode
+    {
+            bool mTrue;
+
+        public:
+
+            BooleanNode (bool true_);
+
+            virtual bool test (const CSMWorld::IdTable& table, int row,
+                const std::map<std::string, const Node *>& otherFilters,
+                const std::map<int, int>& columns,
+                const std::string& userValue) const;
+            ///< \return Can the specified table row pass through to filter?
+            /// \param columns column ID to column index mapping
+
+            virtual std::string toString (bool numericColumns) const;
+            ///< Return a string that represents this node.
+            ///
+            /// \param numericColumns Use numeric IDs instead of string to represent columns.
+
+    };
+}
+
+#endif
\ No newline at end of file
diff --git a/apps/opencs/model/filter/leafnode.cpp b/apps/opencs/model/filter/leafnode.cpp
new file mode 100644
index 000000000..5c6d4b042
--- /dev/null
+++ b/apps/opencs/model/filter/leafnode.cpp
@@ -0,0 +1,22 @@
+
+#include "leafnode.hpp"
+
+std::vector<std::string> CSMFilter::LeafNode::getReferencedFilters() const
+{
+    return std::vector<std::string>();
+}
+
+std::vector<int> CSMFilter::LeafNode::getReferencedColumns() const
+{
+    return std::vector<int>();
+}
+
+bool CSMFilter::LeafNode::isSimple() const
+{
+    return true;
+}
+
+bool CSMFilter::LeafNode::hasUserValue() const
+{
+    return false;
+}
\ No newline at end of file
diff --git a/apps/opencs/model/filter/leafnode.hpp b/apps/opencs/model/filter/leafnode.hpp
new file mode 100644
index 000000000..663083ff9
--- /dev/null
+++ b/apps/opencs/model/filter/leafnode.hpp
@@ -0,0 +1,29 @@
+#ifndef CSM_FILTER_UNARIYNODE_H
+#define CSM_FILTER_UNARIYNODE_H
+
+#include <memory>
+
+#include "node.hpp"
+
+namespace CSMFilter
+{
+    class LeafNode : public Node
+    {
+        public:
+
+            virtual std::vector<std::string> getReferencedFilters() const;
+            ///< Return a list of filters that are used by this node (and must be passed as
+            /// otherFilters when calling test).
+
+            virtual std::vector<int> getReferencedColumns() const;
+            ///< Return a list of the IDs of the columns referenced by this node. The column mapping
+            /// passed into test as columns must contain all columns listed here.
+
+            virtual bool isSimple() const;
+            ///< \return Can this filter be displayed in simple mode.
+
+            virtual bool hasUserValue() const;
+    };
+}
+
+#endif
diff --git a/apps/opencs/model/filter/node.cpp b/apps/opencs/model/filter/node.cpp
new file mode 100644
index 000000000..276861cdc
--- /dev/null
+++ b/apps/opencs/model/filter/node.cpp
@@ -0,0 +1,6 @@
+
+#include "node.hpp"
+
+CSMFilter::Node::Node() {}
+
+CSMFilter::Node::~Node() {}
\ No newline at end of file
diff --git a/apps/opencs/model/filter/node.hpp b/apps/opencs/model/filter/node.hpp
new file mode 100644
index 000000000..09bc3cd42
--- /dev/null
+++ b/apps/opencs/model/filter/node.hpp
@@ -0,0 +1,58 @@
+#ifndef CSM_FILTER_NODE_H
+#define CSM_FILTER_NODE_H
+
+#include <string>
+#include <map>
+#include <vector>
+
+namespace CSMWorld
+{
+    class IdTable;
+}
+
+namespace CSMFilter
+{
+    /// \brief Root class for the filter node hierarchy
+    ///
+    /// \note When the function documentation for this class mentions "this node", this should be
+    /// interpreted as "the node and all its children".
+    class Node
+    {
+            // not implemented
+            Node (const Node&);
+            Node& operator= (const Node&);
+
+        public:
+
+            Node();
+
+            virtual ~Node();
+
+            virtual bool test (const CSMWorld::IdTable& table, int row,
+                const std::map<std::string, const Node *>& otherFilters,
+                const std::map<int, int>& columns,
+                const std::string& userValue) const = 0;
+            ///< \return Can the specified table row pass through to filter?
+            /// \param columns column ID to column index mapping
+
+            virtual std::vector<std::string> getReferencedFilters() const = 0;
+            ///< Return a list of filters that are used by this node (and must be passed as
+            /// otherFilters when calling test).
+
+            virtual std::vector<int> getReferencedColumns() const = 0;
+            ///< Return a list of the IDs of the columns referenced by this node. The column mapping
+            /// passed into test as columns must contain all columns listed here.
+
+            virtual bool isSimple() const = 0;
+            ///< \return Can this filter be displayed in simple mode.
+
+            virtual bool hasUserValue() const = 0;
+
+            virtual std::string toString (bool numericColumns) const = 0;
+            ///< Return a string that represents this node.
+            ///
+            /// \param numericColumns Use numeric IDs instead of string to represent columns.
+    };
+}
+
+#endif
diff --git a/apps/opencs/model/filter/unarynode.cpp b/apps/opencs/model/filter/unarynode.cpp
new file mode 100644
index 000000000..f9cc3fdc8
--- /dev/null
+++ b/apps/opencs/model/filter/unarynode.cpp
@@ -0,0 +1,34 @@
+
+#include "unarynode.hpp"
+
+CSMFilter::UnaryNode::UnaryNode (std::auto_ptr<Node> child) : mChild (child) {}
+
+const CSMFilter::Node& CSMFilter::UnaryNode::getChild() const
+{
+    return *mChild;
+}
+
+CSMFilter::Node& CSMFilter::UnaryNode::getChild()
+{
+    return *mChild;
+}
+
+std::vector<std::string> CSMFilter::UnaryNode::getReferencedFilters() const
+{
+    return mChild->getReferencedFilters();
+}
+
+std::vector<int> CSMFilter::UnaryNode::getReferencedColumns() const
+{
+    return mChild->getReferencedColumns();
+}
+
+bool CSMFilter::UnaryNode::isSimple() const
+{
+    return false;
+}
+
+bool CSMFilter::UnaryNode::hasUserValue() const
+{
+    return mChild->hasUserValue();
+}
diff --git a/apps/opencs/model/filter/unarynode.hpp b/apps/opencs/model/filter/unarynode.hpp
new file mode 100644
index 000000000..6ecad1192
--- /dev/null
+++ b/apps/opencs/model/filter/unarynode.hpp
@@ -0,0 +1,37 @@
+#ifndef CSM_FILTER_UNARIYNODE_H
+#define CSM_FILTER_UNARIYNODE_H
+
+#include <memory>
+
+#include "node.hpp"
+
+namespace CSMFilter
+{
+    class UnaryNode : public Node
+    {
+            std::auto_ptr<Node> mChild;
+
+        public:
+
+            UnaryNode (std::auto_ptr<Node> child);
+
+            const Node& getChild() const;
+
+            Node& getChild();
+
+            virtual std::vector<std::string> getReferencedFilters() const;
+            ///< Return a list of filters that are used by this node (and must be passed as
+            /// otherFilters when calling test).
+
+            virtual std::vector<int> getReferencedColumns() const;
+            ///< Return a list of the IDs of the columns referenced by this node. The column mapping
+            /// passed into test as columns must contain all columns listed here.
+
+            virtual bool isSimple() const;
+            ///< \return Can this filter be displayed in simple mode.
+
+            virtual bool hasUserValue() const;
+    };
+}
+
+#endif