Index: parse.py
==================================================================
--- parse.py
+++ parse.py
@@ -1,6 +1,8 @@
 #!/usr/bin/env python
+
+import tree
 
 from ply import lex, yacc
 class Note():
     def __init__(self, value, duration=.25, octave=8):
         self.value = value
@@ -35,10 +37,11 @@
         "ACCIDENTAL",
         "REST",
         "OCTAVE",
         "CHORD_TYPE",
         "QUOTE",
+        "NODE",
     )
 
     t_ignore = " |"
 
     #t_BASENOTE = r"[A-Ga-g]"
@@ -47,10 +50,11 @@
     t_ACCIDENTAL = r"\^{1,2}|_{1,2}|="
     t_REST = r"z"
     t_OCTAVE = r"'+|,+"
     t_CHORD_TYPE = r"m|7|m7|0|o|\+|mb5|sus|sus4|maj7|mmaj7|7sus4|dim|dim7|7b5|m7b5|6|b6|m6|mb6|46|maj9|9|add9|7b9|m9"
     t_QUOTE = '"'
+    t_NODE = r"([a-zA-Z0-9_-]+)"
 
     def t_NOTE_LENGTH(t):
         r"/?\d+"
         multiplier = float(t.value.strip("/"))
         if t.value.startswith("/"):
@@ -77,17 +81,19 @@
 
     def p_pitch_list(p):
         '''score : score note
             | score chord
             | score rest
+            | score node
         '''
         p[0] = p[1] + [p[2]]
 
     def p_score(p):
         '''score : note
             | chord
             | rest
+            | node
         '''
         p[0] = [p[1]]
 
 
     def p_note(p):
@@ -146,13 +152,19 @@
                 | REST NOTE_LENGTH
         '''
         p[0] = Rest()
         if len(p) > 2:
             p[0].duration = p[2]
+
+    def node(p):
+        '''node: NODE
+        '''
+        p[0] = tree.tree(node.strip("(").strip(")"))
+
 
     def p_error(p):
         raise Exception("Syntax error at '%s' of element type %s" % (p.value, p.type))
         
     yacc.yacc()
 
     #print yacc.parse("GFG B'AB,, | g/2fg gab | GFG BAB | d2A AFD")
     return yacc.parse(score)

ADDED   tree.py
Index: tree.py
==================================================================
--- /dev/null
+++ tree.py
@@ -0,0 +1,31 @@
+import pdb
+
+class Tree():
+    def __init__(self):
+        self.nodes = []
+
+    def traverse_depth_first(self):
+        all_nodes = []
+        for node in self.nodes:
+            if isinstance(node, Node):
+                all_nodes.append(node)
+            elif isinstance(node, Tree):
+#                pdb.set_trace()
+                all_nodes.extend(node.traverse_depth_first())
+        return all_nodes
+
+    def __str__(self):
+        return str(self.__unicode__())
+    def __unicode__(self):
+        return self.nodes
+
+
+class Node():
+    def __init__(self, parent, data):
+        self.parent = parent
+        self.data = data
+
+    def __str__(self):
+        return str(self.__unicode__())
+    def __unicode__(self):
+        return self.data