diff --git a/btree.cpp b/btree.cpp
index fc91806..8635805 100644
--- a/btree.cpp
+++ b/btree.cpp
@@ -36,6 +36,11 @@
 } // bTree::calcSize
 
 void
+bTree::setNull(uPtr & u) {
+  u.offset = 0;
+} // bTree::setNull
+
+void
 bTree::InstallUserFunctions(compareKeyFunc cmpFunc, copyKeyProc copyProc, keySizeFunc ksFunc) {
   compareKey = cmpFunc;
   copyKey = copyProc;
diff --git a/btree.h b/btree.h
index 017aa68..371be63 100644
--- a/btree.h
+++ b/btree.h
@@ -5,66 +5,6 @@
 #include "btree_vfs.h"   // bTreeVFS class
 #include "btree_key.h"   // bTree key functions
 
-enum treeTypes { BT_CUSTOM, BT_PCHAR, BT_STRING, BT_SINGLE, BT_DOUBLE, BT_INT32, BT_INT64 };
-
-typedef struct TblockRun {
-  int32  AG;
-  uInt16 start;
-  uInt16 len;
-} __attribute__((__packed__));
-
-typedef TblockRun inodeAddr;
-
-typedef union {
-  int32     i;
-  uInt32    u;
-  float     f;
-  double    d;
-  void *    p;
-  inodeAddr iAddr;
-  int64     offset;
-} uPtr;  
-
-typedef struct bTreeSearch {
-  uPtr      value;
-  void *    key;
-  int       keySize;
-}; // bTreeSearchRec
-
-typedef struct bTreeInfo {
-  int64     magic;
-  uPtr      root;
-  uPtr      firstDeleted;
-  uInt32    nodes;
-  uInt32    height;
-  uInt32    keys;
-  uInt32    bNodeSize;
-  treeTypes treeType;
-} __attribute__((__packed__));
-
-typedef struct TbNodeData {
-  uPtr      link;
-  union {
-    char    str[1];
-    float   f;
-    double  d;
-    int32   i;
-    int64   x;
-  } key;
-} __attribute__((__packed__));
-
-typedef struct TbNode {
-  uInt32    magic;
-  uInt32    tag;
-  uInt32    numKeys;
-  uInt32    size;
-  uPtr      left;
-  uPtr      right;
-  uPtr      parent;
-  uPtr      reserved;
-  TbNodeData data;
-} __attribute__((__packed__));
-
 class bTree {
  protected:
   compareKeyFunc compareKey;
@@ -77,6 +17,7 @@
 
   int      align(int);
   int      calcSize(TbNode *);
+  void     setNull(uPtr &);
  public:
            bTree(char *, uInt32, treeTypes, bTreeVFS *);
   void     InstallUserFunctions(compareKeyFunc, copyKeyProc, keySizeFunc);  
diff --git a/btree_types.h b/btree_types.h
index 7e0f379..e2d14b6 100644
--- a/btree_types.h
+++ b/btree_types.h
@@ -10,4 +10,64 @@
 typedef unsigned int           uInt32;
 typedef unsigned long long int uInt64;
 
+enum treeTypes { BT_CUSTOM, BT_PCHAR, BT_STRING, BT_SINGLE, BT_DOUBLE, BT_INT32, BT_INT64 };
+
+typedef struct TblockRun {
+  int32  AG;
+  uInt16 start;
+  uInt16 len;
+} __attribute__((__packed__));
+
+typedef TblockRun inodeAddr;
+
+typedef union {
+  int32     i;
+  uInt32    u;
+  float     f;
+  double    d;
+  void *    p;
+  inodeAddr iAddr;
+  int64     offset;
+} uPtr;
+
+typedef struct bTreeSearch {
+  uPtr      value;
+  void *    key;
+  int       keySize;
+}; // bTreeSearchRec
+
+typedef struct bTreeInfo {
+  int64     magic;
+  uPtr      root;
+  uPtr      firstDeleted;
+  uInt32    nodes;
+  uInt32    height;
+  uInt32    keys;
+  uInt32    bNodeSize;
+  treeTypes treeType;
+} __attribute__((__packed__));
+
+typedef struct TbNodeData {
+  uPtr      link;
+  union {
+    char    str[1];
+    float   f;
+    double  d;
+    int32   i;
+    int64   x;
+  } key;
+} __attribute__((__packed__));
+
+typedef struct TbNode {
+  uInt32    magic;
+  uInt32    tag;
+  uInt32    numKeys;
+  uInt32    size;
+  uPtr      left;
+  uPtr      right;
+  uPtr      parent;
+  uPtr      reserved;
+  TbNodeData data;
+} __attribute__((__packed__));
+
 #endif