diff --git a/PythonicGcodeMachine/Gcode/Rs274/Ast.py b/PythonicGcodeMachine/Gcode/Rs274/Ast.py
index bfd7733097e2103fb765dc65c510ea4630513d3f..4ef47023eccf2bdc4f5aaaf9d499b4506a343c34 100644
--- a/PythonicGcodeMachine/Gcode/Rs274/Ast.py
+++ b/PythonicGcodeMachine/Gcode/Rs274/Ast.py
@@ -261,6 +261,18 @@ class Line:
 
     ##############################################
 
+    def iter_on_word(self):
+        for item in self:
+            if isinstance(item, Word):
+                yield item
+
+    def iter_on_setting(self):
+        for item in self:
+            if isinstance(item, ParameterSetting):
+                yield item
+
+    ##############################################
+
     def __repr__(self):
 
         items = []
diff --git a/PythonicGcodeMachine/Gcode/Rs274/Config.py b/PythonicGcodeMachine/Gcode/Rs274/Config.py
index 8d7f2551d53a793bc2387ac4088157d4039b7a66..f05140da56f28e873abd32f257ab810655bd2bd7 100644
--- a/PythonicGcodeMachine/Gcode/Rs274/Config.py
+++ b/PythonicGcodeMachine/Gcode/Rs274/Config.py
@@ -135,8 +135,7 @@ class Letters(YamlMixin):
         data = self._load_yaml(yaml_path)
         self._letters = {}
         for letter, d in data.items():
-            letter = Letter(letter, d['meaning'])
-            self._letters[letter] = letter
+            self._letters[letter] = Letter(letter, d['meaning'])
 
     ##############################################
 
diff --git a/PythonicGcodeMachine/Gcode/Rs274/Parser.py b/PythonicGcodeMachine/Gcode/Rs274/Parser.py
index 681d1c286dc19351aebacc9393bd8aca6177dfcc..fdeea7c300c6f3b76e247c1ac4e2a23a9bf4316b 100644
--- a/PythonicGcodeMachine/Gcode/Rs274/Parser.py
+++ b/PythonicGcodeMachine/Gcode/Rs274/Parser.py
@@ -395,9 +395,16 @@ class GcodeParserMixin:
         Return a :class:`PythonicGcodeMachine.Gcode.Rs274.Ast.Program` instance.
         """
 
+        if not isinstance(lines, (list, tuple)):
+            lines = lines.split('\n')
+
         program = Ast.Program()
-        for line in lines.split('\n'):
-            program += self.parse(line)
+        for line in lines:
+            try:
+                program += self.parse(line)
+            except GcodeParserError as exception:
+                print('Parse Error:', line)
+                raise exception
 
         return program
 
diff --git a/examples/annotate-gcode.py b/examples/annotate-gcode.py
new file mode 100644
index 0000000000000000000000000000000000000000..99cfcc975f88fcbf63eb7d8b8852dbd8cc163c5e
--- /dev/null
+++ b/examples/annotate-gcode.py
@@ -0,0 +1,37 @@
+####################################################################################################
+
+"""Example to show how to annote a G-code program.
+"""
+
+####################################################################################################
+
+from pathlib import Path
+
+from PythonicGcodeMachine.Gcode.Rs274 import GcodeParser, gcodes, letters
+
+####################################################################################################
+
+program_filename = 'mill-example-1.ngc'
+
+programs_directory = Path(__file__).parent.joinpath('programs')
+program_path = programs_directory.joinpath(program_filename)
+with open(program_path, 'r') as fh:
+    lines = fh.readlines()
+    if lines[0].startswith(';'):
+        lines = lines[1:]
+
+parser = GcodeParser()
+program = parser.parse_lines(lines)
+
+meaning_format = '  {:5}: {}'
+for line in program:
+    print()
+    print(line.ansi_str())
+    for word in line.iter_on_word():
+        if word.letter in 'GM':
+            meaning = gcodes[str(word)].meaning
+            print(meaning_format.format(str(word), meaning))
+        else:
+            letter = word.letter
+            meaning = letters[letter].meaning
+            print(meaning_format.format(letter, meaning))
diff --git a/examples/programs/mill-example-1.ngc b/examples/programs/mill-example-1.ngc
new file mode 100644
index 0000000000000000000000000000000000000000..d5d5a17b0b4d4d2529b19c583a883af03da659b3
--- /dev/null
+++ b/examples/programs/mill-example-1.ngc
@@ -0,0 +1,16 @@
+; http://www.helmancnc.com/cnc-mill-example-program-g01-g02-g03-g90-g91
+N40 G90 G00 X0 Y0
+N50 G01 X-10 Y-20 R8         (P1)
+N60 G01 X-50 R10             (P2)
+N70 Y10                      (P3)
+N80 X-19.97 Y25.01           (P4)
+N90 G03 X7.97 Y38.99 R18     (P5)
+N100 G01 X30 Y50             (P6)
+N110 G91 X10.1 Y-10.1        (P7)
+N120 G90 G02 X59.9 Y20.1 R14 (P8)
+N130 G01 X70 Y10             (P9)
+N140 Y-20 R10                (P10)
+N150 X50                     (P11)
+N160 G03 X30 R10             (P12)
+N170 G01 X10 R8              (P13)
+N180 X0 Y0