new file mode 100644
--- /dev/null
+++ b/src/pt-id.h
@@ -0,0 +1,126 @@
+/*
+
+Copyright (C) 1996, 1997 John W. Eaton
+
+This file is part of Octave.
+
+Octave 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, or (at your option) any
+later version.
+
+Octave 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 Octave; see the file COPYING.  If not, write to the Free
+Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+*/
+
+#if !defined (octave_tree_identifier_h)
+#define octave_tree_identifier_h 1
+
+#if defined (__GNUG__)
+#pragma interface
+#endif
+
+class ostream;
+
+#include <string>
+
+class octave_symbol;
+class octave_function;
+class symbol_record;
+
+class tree_walker;
+
+#include "pt-mvr-base.h"
+
+// Symbols from the symbol table.
+
+class
+tree_identifier : public tree_multi_val_ret
+{
+  friend class tree_index_expression;
+
+public:
+
+  tree_identifier (int l = -1, int c = -1)
+    : tree_multi_val_ret (l, c), sym (0), maybe_do_ans_assign (false) { }
+
+  tree_identifier (symbol_record *s, int l = -1, int c = -1)
+    : tree_multi_val_ret (l, c), sym (s), maybe_do_ans_assign (false) { }
+
+  ~tree_identifier (void) { }
+
+  bool is_identifier (void) const
+    { return true; }
+
+  string name (void) const;
+
+  tree_identifier *define (octave_symbol *s, unsigned int sym_type);
+
+  tree_identifier *define (octave_function *f, unsigned int sym_type);
+
+  tree_identifier *define (const octave_value& v);
+
+  void document (const string& s);
+
+  octave_value assign (octave_value::assign_op op,
+		       const octave_value& t);
+
+  octave_value assign (octave_value::assign_op op,
+		       const octave_value_list& args,
+		       const octave_value& t);
+
+  bool is_defined (void);
+
+  void increment (void);
+
+  void decrement (void);
+
+  octave_symbol *do_lookup (bool& script_file_executed, bool
+			    exec_script = true);
+
+  void link_to_global (void);
+
+  void mark_as_static (void);
+
+  void mark_as_formal_parameter (void);
+
+  void mark_for_possible_ans_assign (void)
+    { maybe_do_ans_assign = true; }
+
+  octave_value eval (bool print = false);
+
+  octave_value_list eval (bool print, int nargout,
+			  const octave_value_list& args); 
+
+  void eval_undefined_error (void);
+
+  void accept (tree_walker& tw);
+
+  octave_value value (void) const;
+
+  octave_value& reference (void);
+
+private:
+
+  // The symbol record that this identifier references.
+  symbol_record *sym;
+
+  // True if we should consider assigning the result of evaluating
+  // this identifier to the built-in variable ans.
+  bool maybe_do_ans_assign;
+};
+
+#endif
+
+/*
+;;; Local Variables: ***
+;;; mode: C++ ***
+;;; End: ***
+*/