diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..2d2015f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+# python cache / compilations
+*__pycache__
+*.pyc
+
+# editor backups
+*.swp
diff --git a/README.md b/README.md
index 4a8a505..cc50c33 100644
--- a/README.md
+++ b/README.md
@@ -16,16 +16,19 @@ Just brainstorming here...
     import math
     import euclid
 
-    gfile_in = pygcode.Parser('part.gcode')
-    gfile_out = pygcode.Writer('part2.gcode')
+    gfile_in = pygcode.parse('part1.gcode') #
+    gfile_out = pygcode.GCodeFile('part2.gcode')
 
     total_travel = 0
     total_time = 0
 
-    for (state, block) in gfile_in.iterstate():
-        # where:
-        #   state = CNC's state before the block is executed
-        #   block = the gcode to be executed next
+    machine = pygcode.Machine()
+
+    for line in gfile_in.iterlines():
+
+        block = line.block
+        if block is None:
+            continue
 
         # validation
         if isinstance(block, pygcode.GCodeArc):
@@ -36,13 +39,13 @@ Just brainstorming here...
                 block.set_precision(0.0005, method=pygcode.GCodeArc.EFFECT_RADIUS)
 
         # random metrics
-        travel_vector = block.position - state.position # euclid.Vector3 instance
+        travel_vector = block.position - machine.state.position # euclid.Vector3 instance
         distance = travel_vector.magnitude()
-        travel = block.travel_distance(position=state.position) # eg: distance != travel for G02 & G03
+        travel = block.travel_distance(position=machine.state.position) # eg: distance != travel for G02 & G03
 
         total_travel += travel
-        #total_time += block.time(feed_rate=state.feed_rate) # doesn't consider the feedrate being changed in this block
-        total_time += block.time(state=state)
+        #total_time += block.time(feed_rate=machine.state.feed_rate) # doesn't consider the feedrate being changed in this block
+        total_time += block.time(state=machine.state)
 
         # rotate : entire file 90deg CCW
         block.rotate(euclid.Quaternion.new_rotate_axis(
@@ -51,6 +54,8 @@ Just brainstorming here...
         # translate : entire file x += 1, y += 2 mm (after rotation)
         block.translate(euclid.Vector3(1, 2, 0), unit=pygcode.UNIT_MM)
 
+
+
         # TODO: then do something like write it to another file
         gfile_out.write(block)
 
@@ -59,7 +64,7 @@ Just brainstorming here...
 
 
 ## Supported G-Codes
-GCode support is planned to follow that of [GRBL](https://github.com/gnea/grbl).
+GCode support is planned to follow that of [GRBL](https://github.com/gnea/grbl) which follows [LinuxCNC](http://linuxcnc.org) (list of gcodes documented [here](http://linuxcnc.org/docs/html/gcode.html)).
 
 But anything pre v1.0 will be a sub-set, focusing on the issues I'm having... I'm selfish that way.
 
diff --git a/pygcode/__init__.py b/pygcode/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/pygcode/block.py b/pygcode/block.py
new file mode 100644
index 0000000..6018fd3
--- /dev/null
+++ b/pygcode/block.py
@@ -0,0 +1,36 @@
+import re
+from .words import iter_words, WORD_MAP
+
+class Block(object):
+    """GCode block (effectively any gcode file line that defines any <word><value>)"""
+
+    def __init__(self, text):
+        """
+        Block Constructor
+        :param A-Z: gcode parameter values
+        :param comment: comment text
+        """
+
+        self._raw_text = text  # unaltered block content (before alteration)
+
+        # clean up block string
+        text = re.sub(r'(^\s+|\s+$)', '', text) # remove whitespace padding
+        text = re.sub(r'\s+', ' ', text) # remove duplicate whitespace with ' '
+
+        self.text = text
+
+        self.words = list(iter_words(self.text))
+
+    def __getattr__(self, k):
+        if k in WORD_MAP:
+            for w in self.words:
+                if w.letter == k:
+                    return w
+            # if word is not in this block:
+            return None
+
+        else:
+            raise AttributeError("'{cls}' object has no attribute '{key}'".format(
+                cls=self.__class__.__name__,
+                key=k
+            ))
diff --git a/pygcode/comment.py b/pygcode/comment.py
new file mode 100644
index 0000000..dfae3ed
--- /dev/null
+++ b/pygcode/comment.py
@@ -0,0 +1,61 @@
+import re
+
+
+class CommentBase(object):
+    ORDER = 0
+    MULTICOMMENT_JOINER = ". " # joiner if multiple comments are found on the same line
+    def __init__(self, text):
+        self.text = text
+
+
+class CommentSemicolon(CommentBase):
+    "Comments of the format: 'G00 X1 Y2 ; something profound'"
+    ORDER = 1
+    AUTO_REGEX = re.compile(r'\s*;\s*(?P<text>.*)$')
+
+    def __str__(self):
+        return "; {text}".format(text=self.text)
+
+
+class CommentBrackets(CommentBase):
+    "Comments of the format: 'G00 X1 Y2 (something profound)"
+    ORDER = 2
+    AUTO_REGEX = re.compile(r'\((?P<text>[^\)]*)\)')
+
+    def __str__(self):
+        return "({text})".format(text=self.text)
+
+
+Comment = CommentBrackets # default comment type
+
+
+def split_line(line_text):
+    """
+    Split functional block content from comments
+    :param line_text: line from gcode file
+    :return: tuple of (str(<functional block code>), CommentBase(<comment(s)>))
+    """
+    comments_class = None
+
+    # Auto-detect comment type if I can
+    comments = []
+    block_str = line_text.rstrip("\n") # to remove potential return carriage from comment body
+
+    for cls in sorted(CommentBase.__subclasses__(), key=lambda c: c.ORDER):
+        matches = list(cls.AUTO_REGEX.finditer(block_str))
+        if matches:
+            for match in reversed(matches):
+                # Build list of comment text
+                comments.insert(0, match.group('text'))  # prepend
+                # Remove comments from given block_str
+                block_str = block_str[:match.start()] + block_str[match.end():]
+            comments_class = cls
+            break
+
+    # Create comment instance if content was found
+    comment_obj = None
+    if comments_class:
+        comment_text = comments_class.MULTICOMMENT_JOINER.join(comments)
+        comment_obj = comments_class(comment_text)
+
+    return (block_str, comment_obj)
diff --git a/pygcode/exceptions.py b/pygcode/exceptions.py
new file mode 100644
index 0000000..0249ff7
--- /dev/null
+++ b/pygcode/exceptions.py
@@ -0,0 +1,7 @@
+
+# ===================== Parsing Exceptions =====================
+class GCodeBlockFormatError(Exception):
+    """Raised when errors encountered while parsing block text"""
+    pass
+
+# ===================== Parsing Exceptions =====================
diff --git a/pygcode/file.py b/pygcode/file.py
new file mode 100644
index 0000000..db99d99
--- /dev/null
+++ b/pygcode/file.py
@@ -0,0 +1,23 @@
+from .line import Line
+
+
+class GCodeFile(object):
+    def __init__(self, filename=None):
+        self.filename = filename
+
+        # Initialize
+        self.lines = []
+
+    def append(self, line):
+        assert isinstance(line, Line), "invalid line type"
+        self.lines.append(line)
+
+
+def parse(filename):
+    # FIXME: should be an iterator, and also not terrible
+    file = GCodeFile()
+    with open(filename, 'r') as fh:
+        for line in fh.readlines():
+            line_obj = Line(line)
+            file.append(line_obj)
+    return file
diff --git a/pygcode/line.py b/pygcode/line.py
new file mode 100644
index 0000000..f12ebd6
--- /dev/null
+++ b/pygcode/line.py
@@ -0,0 +1,28 @@
+from .comment import split_line
+from .block import Block
+
+class Line(object):
+    def __init__(self, text=None):
+        self._text = text
+
+        # Initialize
+        self.block = None
+        self.comment = None
+
+        # Split line into block text, and comments
+        if text is not None:
+            (block_str, comment) = split_line(text)
+            if block_str:
+                self.block = Block(block_str)
+            if comment:
+                self.comment = comment
+
+    @property
+    def text(self):
+        if self._text is None:
+            return self.build_line_text()
+        return self._text
+
+
+    def build_line_text(self):
+        return ' '.join([str(x) for x in [self.block, self.comment] if x]) + '\n'
diff --git a/pygcode/machine.py b/pygcode/machine.py
new file mode 100644
index 0000000..39e49bc
--- /dev/null
+++ b/pygcode/machine.py
@@ -0,0 +1,36 @@
+
+
+class MachineState(object):
+    def __init__(self, axes=('x', 'y', 'z')):
+        self.axes = axes
+
+        # initialize
+        self.position = {}
+        for axis in self.axes:
+            self.position[axis] = 0
+
+        self.time = 0
+
+class Machine(object):
+    """"""
+    def __init__(self, **kwargs):
+        self.axes = kwargs.get('axes', ('x', 'y', 'z'))
+        self.max_rate = kwargs.get('max_rate', {
+            'x': 500, # mm/min
+            'y': 500, # mm/min
+            'z': 500, # mm/min
+        })
+        self.max_travel = kwargs.get('max_travel', {
+            'x': 200, # mm
+            'y': 200, # mm
+            'z': 200, # mm
+        })
+        self.max_spindle_speed = kwargs.get('max_spindle_speed', 1000) # rpm
+        self.min_spindle_speed = kwargs.get('max_spindle_speed', 0) # rpm
+
+        # initialize
+        self.state = MachineState(self.axes)
+
+    def process_line(self, line):
+        """Change machine's state based on the given gcode line"""
+        pass # TODO
diff --git a/pygcode/words.py b/pygcode/words.py
new file mode 100644
index 0000000..cce53eb
--- /dev/null
+++ b/pygcode/words.py
@@ -0,0 +1,321 @@
+import re
+import itertools
+import six
+
+from .exceptions import GCodeBlockFormatError
+
+FLOAT_REGEX = re.compile(r'^-?\d+(\.\d+)?')
+INT_REGEX = re.compile(r'^-?\d+')
+POSITIVEINT_REGEX = re.compile(r'^\d+')
+
+WORD_MAP = {
+    # Descriptions copied from wikipedia:
+    #   https://en.wikipedia.org/wiki/G-code#Letter_addresses
+
+    # Rotational Axes
+    'A': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Absolute or incremental position of A axis (rotational axis around X axis)",
+    },
+    'B': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Absolute or incremental position of B axis (rotational axis around Y axis)",
+    },
+    'C': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Absolute or incremental position of C axis (rotational axis around Z axis)",
+    },
+    'D': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Defines diameter or radial offset used for cutter compensation. D is used for depth of cut on lathes. It is used for aperture selection and commands on photoplotters.",
+    },
+    # Feed Rates
+    'E': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Precision feedrate for threading on lathes",
+    },
+    'F': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Feedrate",
+    },
+    # G-Codes
+    'G': {
+        'class': str,
+        'value_regex': re.compile(r'^\d+(\.\d+)?'),
+        'description': "Address for preparatory commands",
+    },
+    # Tool Offsets
+    'H': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Defines tool length offset; Incremental axis corresponding to C axis (e.g., on a turn-mill)",
+    },
+    # Arc radius center coords
+    'I': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Defines arc center in X axis for G02 or G03 arc commands. Also used as a parameter within some fixed cycles.",
+    },
+    'J': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Defines arc center in Y axis for G02 or G03 arc commands. Also used as a parameter within some fixed cycles.",
+    },
+    'K': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Defines arc center in Z axis for G02 or G03 arc commands. Also used as a parameter within some fixed cycles, equal to L address.",
+    },
+    # Loop Count
+    'L': {
+        'class': int,
+        'value_regex': POSITIVEINT_REGEX,
+        'description': "Fixed cycle loop count; Specification of what register to edit using G10",
+    },
+    # Miscellaneous Function
+    'M': {
+        'class': str,
+        'value_regex': re.compile(r'^\d+(\.\d+)?'),
+        'description': "Miscellaneous function",
+    },
+    # Line Number
+    'N': {
+        'class': int,
+        'value_regex': POSITIVEINT_REGEX,
+        'description': "Line (block) number in program; System parameter number to change using G10",
+    },
+    # Program Name
+    'O': {
+        'class': str,
+        'value_regex': re.compile(r'^.+$'), # all the way to the end
+        'description': "Program name",
+    },
+    # Parameter (arbitrary parameter)
+    'P': {
+        'class': float, # parameter is often an integer, but can be a float
+        'value_regex': FLOAT_REGEX,
+        'description': "Serves as parameter address for various G and M codes",
+    },
+    # Peck increment
+    'Q': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Depth to increase on each peck; Peck increment in canned cycles",
+    },
+    # Arc Radius
+    'R': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Defines size of arc radius, or defines retract height in milling canned cycles",
+    },
+    # Spindle speed
+    'S': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Defines speed, either spindle speed or surface speed depending on mode",
+    },
+    # Tool Selecton
+    'T': {
+        'class': str,
+        'value_regex': POSITIVEINT_REGEX, # tool string may have leading '0's, but is effectively an index (integer)
+        'description': "Tool selection",
+    },
+    # Incremental axes
+    'U': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Incremental axis corresponding to X axis (typically only lathe group A controls) Also defines dwell time on some machines (instead of 'P' or 'X').",
+    },
+    'V': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Incremental axis corresponding to Y axis",
+    },
+    'W': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Incremental axis corresponding to Z axis (typically only lathe group A controls)",
+    },
+    # Linear Axes
+    'X': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Absolute or incremental position of X axis.",
+    },
+    'Y': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Absolute or incremental position of Y axis.",
+    },
+    'Z': {
+        'class': float,
+        'value_regex': FLOAT_REGEX,
+        'description': "Absolute or incremental position of Z axis.",
+    },
+}
+
+
+ORDER_LINUXCNC_LETTER_MAP = {
+    'O': 10,
+    'F': 40,
+    'S': 50,
+    'T': 60,
+}
+
+_v_csv = lambda v, ks: [(k, v) for k in ks.split(',')]
+
+ORDER_LINUXCNC_LETTERVALUE_MAP = dict(itertools.chain.from_iterable([
+    _v_csv(30, 'G93,G94'),
+    _v_csv(70, 'M62,M63,M64,M65,M66,M67,M68'),
+    _v_csv(80, 'M6,M61'),
+    _v_csv(90, 'M3,M4,M5'),
+    _v_csv(100, 'M71,M73,M72,M71'),
+    _v_csv(110, 'M7,M8,M9'),
+    _v_csv(120, 'M48,M49,M50,M51,M52,M53'),
+    [('G4', 140)],
+    _v_csv(150, 'G17,G18,G19'),
+    _v_csv(160, 'G20,G21'),
+    _v_csv(170, 'G40,G41,G42'),
+    _v_csv(180, 'G43,G49'),
+    _v_csv(190, 'G54,G55,G56,G57,G58,G59,G59.1,G59.2,G59.3'),
+    _v_csv(200, 'G61,G61.1,G64'),
+    _v_csv(210, 'G90,G91'),
+    _v_csv(220, 'G98,G99'),
+    _v_csv(230, 'G28,G30,G10,G92,G92.1,G92.2,G94'),
+    _v_csv(240, 'G0,G1,G2,G3,G33,G73,G76,G80,G81,G82,G83,G84,G85,G86,G87,G88,G89'),
+    _v_csv(250, 'M0,M1,M2,M30,M60'),
+]))
+
+def _word_order_linuxcnc(word):
+    '''
+    Order taken http://linuxcnc.org/docs/html/gcode/overview.html#_g_code_order_of_execution
+        (as of 2017-07-03)
+    010: O-word commands (optionally followed by a comment but no other words allowed on the same line)
+    N/A: Comment (including message)
+    030: Set feed rate mode (G93, G94).
+    040: Set feed rate (F).
+    050: Set spindle speed (S).
+    060: Select tool (T).
+    070: HAL pin I/O (M62-M68).
+    080: Change tool (M6) and Set Tool Number (M61).
+    090: Spindle on or off (M3, M4, M5).
+    100: Save State (M70, M73), Restore State (M72), Invalidate State (M71).
+    110: Coolant on or off (M7, M8, M9).
+    120: Enable or disable overrides (M48, M49,M50,M51,M52,M53).
+    130: User-defined Commands (M100-M199).
+    140: Dwell (G4).
+    150: Set active plane (G17, G18, G19).
+    160: Set length units (G20, G21).
+    170: Cutter radius compensation on or off (G40, G41, G42)
+    180: Cutter length compensation on or off (G43, G49)
+    190: Coordinate system selection (G54, G55, G56, G57, G58, G59, G59.1, G59.2, G59.3).
+    200: Set path control mode (G61, G61.1, G64)
+    210: Set distance mode (G90, G91).
+    220: Set retract mode (G98, G99).
+    230: Go to reference location (G28, G30) or change coordinate system data (G10) or set axis offsets (G92, G92.1, G92.2, G94).
+    240: Perform motion (G0 to G3, G33, G38.x, G73, G76, G80 to G89), as modified (possibly) by G53.
+    250: Stop (M0, M1, M2, M30, M60).
+    900 + letter val: (else)
+    '''
+    if word.letter in ORDER_LINUXCNC_LETTER_MAP:
+        return ORDER_LINUXCNC_LETTER_MAP[word.letter]
+    letter_value = str(word)
+    if letter_value in ORDER_LINUXCNC_LETTERVALUE_MAP:
+        return ORDER_LINUXCNC_LETTERVALUE_MAP[letter_value]
+
+    # special cases
+    if (word.letter == 'M') and (100 <= int(word.value) <= 199):
+        return 130
+    if (word.letter == 'G') and (38 < float(word.value) < 39):
+        return 240
+
+    # otherwise, sort last, in alphabetic order
+    return (900 + (ord(word.letter) - ord('A')))
+
+def by_linuxcnc_order(word):
+    return word.orderval_linuxcnc
+
+
+class Word(object):
+    def __init__(self, letter, value):
+        self.letter = letter.upper()
+
+        self._value_str = None
+        self._value = None
+        if isinstance(value, six.string_types):
+            self._value_str = value
+        else:
+            self._value = value
+
+        # Sorting Order
+        self._order_linuxcnc = None
+
+    def __str__(self):
+        return "{letter}{value}".format(
+            letter=self.letter,
+            value=self.value_str,
+        )
+
+    # Value Properties
+    @property
+    def value_str(self):
+        """Value string, or """
+        if self._value_str is None:
+            return str(self._value)
+        return self._value_str
+
+    @property
+    def value(self):
+        if self._value is None:
+            return WORD_MAP[self.letter]['class'](self._value_str)
+        return self._value
+
+    # Order
+    @property
+    def orderval_linuxcnc(self):
+        if self._order_linuxcnc is None:
+            self._order_linuxcnc = _word_order_linuxcnc(self)
+        return self._order_linuxcnc
+
+    @property
+    def description(self):
+        return WORD_MAP[self.letter]['description']
+
+NEXT_WORD = re.compile(r'^.*?(?P<letter>[%s])' % ''.join(WORD_MAP.keys()), re.IGNORECASE)
+
+def iter_words(block_text):
+    """
+    Iterate through block text yielding Word instances
+    :param block_text: text for given block with comments removed
+    """
+    index = 0
+
+    while True:
+        letter_match = NEXT_WORD.search(block_text[index:])
+        if letter_match:
+            # Letter
+            letter = letter_match.group('letter').upper()
+            index += letter_match.end() # propogate index to start of value
+
+            # Value
+            value_regex = WORD_MAP[letter]['value_regex']
+            value_match = value_regex.search(block_text[index:])
+            if value_match is None:
+                raise GCodeBlockFormatError("word '%s' value invalid" % letter)
+            value = value_match.group() # matched text
+
+            yield Word(letter, value)
+
+            index += value_match.end() # propogate index to end of value
+        else:
+            break
+
+    remainder = block_text[index:]
+    if remainder and re.search(r'\S', remainder):
+        raise GCodeBlockFormatError("block code remaining '%s'" % remainder)
diff --git a/tests/runtests.sh b/tests/runtests.sh
new file mode 100755
index 0000000..06ad089
--- /dev/null
+++ b/tests/runtests.sh
@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+python -m unittest discover -s . -p 'test_*.py' --verbose
diff --git a/tests/test-files/vertical-slot.ngc b/tests/test-files/vertical-slot.ngc
new file mode 100644
index 0000000..5f8d4b8
--- /dev/null
+++ b/tests/test-files/vertical-slot.ngc
@@ -0,0 +1,26 @@
+T5 M06 G43
+G17 G90 G21
+G00 Z5 S7000 M03
+X9.60 Y48.74
+Z2
+G01 Z-0.5 F100
+G02 X10.75 Y47.44 I-0.11 J-1.26 F70
+G01 X10.75 Y-47.44
+G02 X9.51 Y-48.69 I-1.25 J0
+G02 X8.25 Y-47.44 I0 J1.25
+G01 X8.25 Y-47.44
+X8.25 Y47.44
+G02 X9.6 Y48.74 I1.25 J0.05
+G00 Z5
+Z1.5
+G01 Z-1 F100
+G02 X10.75 Y47.44 I-0.11 J-1.26 F70
+G01 X10.75 Y-47.44
+G02 X9.51 Y-48.69 I-1.25 J0
+G02 X8.25 Y-47.44 I0 J1.25
+G01 X8.25 Y-47.44
+X8.25 Y47.44
+G02 X9.60 Y48.74 I1.25 J0.05
+G00 Z5
+T0 M06 M02
+
diff --git a/tests/test_file.py b/tests/test_file.py
new file mode 100644
index 0000000..30f131e
--- /dev/null
+++ b/tests/test_file.py
@@ -0,0 +1,20 @@
+import sys
+import os
+import inspect
+
+import unittest
+
+# Units Under Test
+_this_path = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe())))
+sys.path.insert(0, os.path.join(_this_path, '..'))
+from pygcode.file import parse, GCodeFile
+
+class FileParseTest(unittest.TestCase):
+    FILENAME = 'test-files/vertical-slot.ngc'
+
+    def test_parser(self):
+        file = parse(self.FILENAME)
+        self.assertEqual(len(file.lines), 26)
+        # FIXME: just verifying content visually
+        for line in file.lines:
+            print(' '.join(["%s%s" % (w.letter, w.value_str) for w in line.block.words]))
diff --git a/tests/test_line.py b/tests/test_line.py
new file mode 100644
index 0000000..2ad74a5
--- /dev/null
+++ b/tests/test_line.py
@@ -0,0 +1,27 @@
+import sys
+import os
+import inspect
+
+import unittest
+
+# Units Under Test
+_this_path = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe())))
+sys.path.insert(0, os.path.join(_this_path, '..'))
+from pygcode.line import Line
+
+
+class LineCommentTests(unittest.TestCase):
+    def test_line_comment_semicolon(self):
+        line = Line('G02 X10.75 Y47.44 I-0.11 J-1.26 F70 ; blah blah')
+        self.assertEqual(line.comment.text, 'blah blah')
+        self.assertEqual(len(line.block.words), 6)
+
+    def test_line_comment_brackets(self):
+        line = Line('G02 X10.75 Y47.44 I-0.11 J-1.26 F70 (blah blah)')
+        self.assertEqual(line.comment.text, 'blah blah')
+        self.assertEqual(len(line.block.words), 6)
+
+    def test_line_comment_brackets_multi(self):
+        line = Line('G02 X10.75 (x coord) Y47.44 (y coord) I-0.11 J-1.26 F70 (eol)')
+        self.assertEqual(line.comment.text, 'x coord. y coord. eol')
+        self.assertEqual(len(line.block.words), 6)
diff --git a/tests/test_words.py b/tests/test_words.py
new file mode 100644
index 0000000..b60ad23
--- /dev/null
+++ b/tests/test_words.py
@@ -0,0 +1,42 @@
+import sys
+import os
+import inspect
+
+import unittest
+
+# Units Under Test
+_this_path = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe())))
+sys.path.insert(0, os.path.join(_this_path, '..'))
+import pygcode.words as gcode_words
+
+#words.iter_words
+
+class WordTests(unittest.TestCase):
+    def test_O(self):
+        pass # TODO
+
+
+
+class WordIterTests(unittest.TestCase):
+    def test_iter1(self):
+        block_str = 'G01 Z-0.5 F100'
+        w = list(gcode_words.iter_words(block_str))
+        # word length
+        self.assertEqual(len(w), 3)
+        # word values
+        self.assertEqual([w[0].letter, w[0].value], ['G', '01'])
+        self.assertEqual([w[1].letter, w[1].value], ['Z', -0.5])
+        self.assertEqual([w[2].letter, w[2].value], ['F', 100])
+
+    def test_iter2(self):
+        block_str = 'G02 X10.75 Y47.44 I-0.11 J-1.26 F70'
+        w = list(gcode_words.iter_words(block_str))
+        # word length
+        self.assertEqual(len(w), 6)
+        # word values
+        self.assertEqual([w[0].letter, w[0].value], ['G', '02'])
+        self.assertEqual([w[1].letter, w[1].value], ['X', 10.75])
+        self.assertEqual([w[2].letter, w[2].value], ['Y', 47.44])
+        self.assertEqual([w[3].letter, w[3].value], ['I', -0.11])
+        self.assertEqual([w[4].letter, w[4].value], ['J', -1.26])
+        self.assertEqual([w[5].letter, w[5].value], ['F', 70])