diff --git a/ba/ba3900.cpp b/ba/ba3900.cpp
new file mode 100755
index 000000000..41fd19419
--- /dev/null
+++ b/ba/ba3900.cpp
@@ -0,0 +1,85 @@
+#include <relapp.h>
+#include <utility.h>
+
+#include "batbinl.h"
+
+class TIndici_app : public TRelation_application
+{ 
+  TRelation* _indici;
+  TMask* _maschera;
+  
+protected:  
+  virtual bool user_create();
+  virtual bool user_destroy();
+  
+  virtual bool changing_mask(int) { return FALSE; }
+  virtual TMask* get_mask(int) { return _maschera; }
+  virtual TRelation* get_relation() const { return _indici; }
+
+  virtual const char* get_next_key();
+  virtual bool save_and_new() const { return TRUE; }
+
+public:
+  TIndici_app() {}
+  virtual ~TIndici_app() {}  
+};
+
+bool TIndici_app::user_create()
+{
+  _indici = new TRelation(LF_INDLIB);
+  _maschera = new TMask("batbinl");
+  return TRUE;
+}
+
+bool TIndici_app::user_destroy()
+{
+  delete _maschera;
+  delete _indici;
+  return TRUE;
+}
+
+const char* TIndici_app::get_next_key()
+{                  
+  const int anno = _maschera->get_int(F_ANNO);
+  const TString16 libro = _maschera->get(F_CODLIB);
+  if (anno == 0 || libro.empty())
+    return "";
+
+  TLocalisamfile index(LF_INDLIB);
+  index.zero();
+  index.put("ANNO", anno);
+  index.put("CODLIB", libro);
+  index.put("NUMREG", 9999999L);
+  
+  long cod = 0;
+  int err = index.read(_isgteq);
+  switch (err)
+  {
+  case _iseof:
+    index.last();
+    err = NOERR;
+    break;
+  case NOERR:  
+    index.prev();
+    break;  
+  default:
+    break;
+  }      
+  
+  if (err == NOERR)
+  {
+    if (index.get_int("ANNO") == anno && index.get("CODLIB") == libro)
+      cod = index.get_long("NUMREG") + 1;    
+  }
+  return (cod > 0) ? format("%d|%d|%d|%s|%d|%ld", 
+                            F_ANNO, anno, F_CODLIB, (const char*)libro, F_INDEX, cod) : "";
+}
+
+
+
+int ba3900(int argc, char* argv[])
+{
+  TIndici_app app;
+  app.run(argc, argv, "Indici libro unico");
+  return 0;
+}