diff --git a/mecode/devices/efd_pico_pulse.py b/mecode/devices/efd_pico_pulse.py
index b52c0a3..a37a138 100644
--- a/mecode/devices/efd_pico_pulse.py
+++ b/mecode/devices/efd_pico_pulse.py
@@ -29,29 +29,29 @@ def disconnect(self):
         self.s.close()
 
     def send(self, command):
-	"""Send message over serial to PicoTouch controller."""
+        """Send message over serial to PicoTouch controller."""
         msg = command + EOT
         self.s.write(msg)
         # return response and remove ACK
         return self.s.read_until(ACK)[:-2]
 
     def set_valve_mode(self, mode):
-	"""Set valve mode to Timed, Purge, Continous, or read current mode.
+        """Set valve mode to Timed, Purge, Continous, or read current mode.
 
-	Keyword argument:
-	mode -- 1 = Timed; 2 = Purge; 3 = Continuous; 5 = read current mode """
+    Keyword argument:
+    mode -- 1 = Timed; 2 = Purge; 3 = Continuous; 5 = read current mode """
         return self.send(str(mode) + 'drv1')
 
     def set_dispense_count(self, count):
-	"""Set how many times valve dispenses with each cycle."""
+        """Set how many times valve dispenses with each cycle."""
         return self.send('{:05}'.format(count) + 'dcn1')
 
     def get_valve_status(self):
-	"""Return valve's current parameters and dispense statistics."""
+        """Return valve's current parameters and dispense statistics."""
         return self.send('rdr1')
 
     def cycle_valve(self):
-	"""Cycle the valve (eqiuvalent to pressing cycle button)."""
+        """Cycle the valve (eqiuvalent to pressing cycle button)."""
         return self.send('1cycl') + self.send('0cycl')
 
     def set_heater_mode(self, mode):
@@ -66,18 +66,18 @@ def set_heater_temp(self, temp):
         return  self.send('{:05.1f}'.format(temp) + 'stmp')
 
     def get_heater_status(self):
-	"""Return mode, heater setpoint temp, and heater actual temp."""
+        """Return mode, heater setpoint temp, and heater actual temp."""
         return self.send('rhtr')
 
     def get_valve_info(self):
-	"""Return controller and valve SN and type, fw version, pcb rev."""
+        """Return controller and valve SN and type, fw version, pcb rev."""
         return self.send('info')
 
     def get_alarm_hist(self):
-	"""Return last 40 alarm conditions with time and alarm name."""
+        """Return last 40 alarm conditions with time and alarm name."""
         return self.send('ralr')
 
     def reset_alarm(self):
-	"""Reset a currently active alarm."""
+        """Reset a currently active alarm."""
         return self.send('arst')
     
diff --git a/mecode/main.py b/mecode/main.py
index 89adb9f..2dceebb 100644
--- a/mecode/main.py
+++ b/mecode/main.py
@@ -110,7 +110,8 @@ def __init__(self, outfile=None, print_lines='auto', header=None, footer=None,
                  extrusion_multiplier=1,
                  setup=True,
                  lineend='os',
-                 comment_char=';'):
+                 comment_char=';',
+                 absolute=False):
         """
         Parameters
         ----------
@@ -179,6 +180,11 @@ def __init__(self, outfile=None, print_lines='auto', header=None, footer=None,
             lineending insertion.
         comment_char : str (default: ';')
             Character to use when outputting comments.
+            Special case handling for parenthesis comments. If "(" is specified
+            as the comment symbol, the comments will be wrapped in both opening
+            and closing parenthesis: `G1 X5 ( this is a comment )`
+        absolute : bool (default: False)
+            Should the system default to relative or absolute mode
 
         """
         self.outfile = outfile
@@ -199,7 +205,7 @@ def __init__(self, outfile=None, print_lines='auto', header=None, footer=None,
         self.i_axis = i_axis
         self.j_axis = j_axis
         self.k_axis = k_axis
-        self.comment_char = comment_char
+        self._comment_char = comment_char
 
         self._current_position = defaultdict(float)
         self.is_relative = True
@@ -237,6 +243,10 @@ def __init__(self, outfile=None, print_lines='auto', header=None, footer=None,
         if setup:
             self.setup()
 
+        if absolute:
+            self.absolute()
+
+
     @property
     def current_position(self):
         return self._current_position
@@ -259,6 +269,54 @@ def __exit__(self, exc_type, exc_value, traceback):
         """
         self.teardown()
 
+    def _commentify(self, txt):
+        '''
+        Format text `txt` in whichever manner is needed to indicate it's a comment.
+        The mode is set by the `comment_char` parameter on class construction
+        '''
+
+        # We need to special case using parenthesis for comments, since we have to 
+        # wrap them around the beginning and the end of the comment
+        if self._comment_char == "(":
+            return "( {} )".format(txt)
+
+        # Otherwise, just prepend the comment character (and a space)
+        return "{} {}".format(self._comment_char, txt)
+
+
+    def write_comment(self, comment):
+        """ Insert a comment into the gcode output file
+        """
+        self.write(self._commentify(comment))
+
+    def move_other_axis(self, a, rapid=False):
+        """ Move an auxilliary axis (currently "A")
+
+        Primarily, this is useful for a rotational indexer (if present)
+        """
+
+        cmd = 'G0 ' if rapid else 'G1 '
+        self.write(cmd + "A{:.{digits}f}".format(a, digits=self.output_digits))
+
+    def insert_machine_stop(self, comment=None):
+        '''Insert a machine stop (M00) command with an optional comment
+        '''
+        if comment:
+            self.write("M00 {}".format(self._commentify(comment)))
+        else:
+            self.write("M00")
+
+    def insert_optional_stop(self, comment=None):
+        '''Insert a optional stop (M01) command with an optional comment
+        '''
+        if comment:
+            self.write("M01 {}".format(self._commentify(comment)))
+        else:
+            self.write("M01")
+
+
+
+
     # GCode Aliases  ########################################################
 
     def set_home(self, x=None, y=None, z=None, **kwargs):
@@ -272,7 +330,7 @@ def set_home(self, x=None, y=None, z=None, **kwargs):
         """
         args = self._format_args(x, y, z, **kwargs)
         space = ' ' if len(args) > 0 else ''
-        self.write('G92' + space + args + ' {}set home'.format(self.comment_char))
+        self.write('G92' + space + args + " " +self._commentify('set home'))
 
         self._update_current_position(mode='absolute', x=x, y=y, z=z, **kwargs)
 
@@ -282,7 +340,7 @@ def reset_home(self):
         # FIXME This does not work with internal current_position
         # FIXME You must call an abs_move after this to re-sync
         # current_position
-        self.write('G92.1 {}reset position to machine coordinates without moving'.format(self.comment_char))
+        self.write('G92.1 {}'.format(self._commentify("reset position to machine coordinates without moving")))
 
     def relative(self):
         """ Enter relative movement mode, in general this method should not be
@@ -290,7 +348,7 @@ def relative(self):
 
         """
         if not self.is_relative:
-            self.write('G91 {}relative'.format(self.comment_char))
+            self.write('G91 {}'.format(self._commentify("relative")))
             self.is_relative = True
 
     def absolute(self):
@@ -299,7 +357,7 @@ def absolute(self):
 
         """
         if self.is_relative:
-            self.write('G90 {}absolute'.format(self.comment_char))
+            self.write('G90 {}'.format(self._commentify("absolute")))
             self.is_relative = False
 
     def feed(self, rate):
@@ -314,7 +372,7 @@ def feed(self, rate):
         self.write('G1 F{}'.format(rate))
         self.speed = rate
 
-    def dwell(self, time):
+    def dwell(self, time, comment=None):
         """ Pause code executions for the given amount of time.
 
         Parameters
@@ -323,7 +381,11 @@ def dwell(self, time):
             Time in milliseconds to pause code execution.
 
         """
-        self.write('G4 P{}'.format(time))
+
+        if comment:
+            self.write('G4 P{} {}'.format(time, self._commentify(comment)))
+        else:
+            self.write('G4 P{}'.format(time))
 
     # Composed Functions  #####################################################
 
@@ -334,9 +396,9 @@ def setup(self):
         """
         self._write_header()
         if self.is_relative:
-            self.write('G91 {}relative'.format(self.comment_char))
+            self.write('G91 {}'.format(self._commentify("relative")))
         else:
-            self.write('G90 {}absolute'.format(self.comment_char))
+            self.write('G90 {}'.format(self._commentify("absolute")))
 
     def teardown(self, wait=True):
         """ Close the outfile file after writing the footer if opened. This
@@ -482,14 +544,14 @@ def arc(self, x=None, y=None, z=None, direction='CW', radius='auto',
             raise RuntimeError(msg)
         dimensions = [k.lower() for k in dims.keys()]
         if 'x' in dimensions and 'y' in dimensions:
-            plane_selector = 'G17 {}XY plane'.format(self.comment_char)  # XY plane
+            plane_selector = 'G17 {}'.format(self._commentify('XY plane'))  # XY plane
             axis = helix_dim
         elif 'x' in dimensions:
-            plane_selector = 'G18 {}XZ plane'.format(self.comment_char)  # XZ plane
+            plane_selector = 'G18 {}'.format(self._commentify('XZ plane'))  # XZ plane
             dimensions.remove('x')
             axis = dimensions[0].upper()
         elif 'y' in dimensions:
-            plane_selector = 'G19 {}YZ plane'.format(self.comment_char)  # YZ plane
+            plane_selector = 'G19 {}'.format(self._commentify('YZ plane'))  # YZ plane
             dimensions.remove('y')
             axis = dimensions[0].upper()
         else:
@@ -539,7 +601,7 @@ def arc(self, x=None, y=None, z=None, direction='CW', radius='auto',
             dims['E'] = filament_length + current_extruder_position
 
         if axis is not None:
-            self.write('G16 X Y {} {}coordinate axis assignment'.format(axis, self.comment_char))  # coordinate axis assignment
+            self.write('G16 X Y {} {}'.format(axis, self._commentify("coordinate axis assignment")))  # coordinate axis assignment
         self.write(plane_selector)
         args = self._format_args(**dims)
         if helix_dim is None:
@@ -582,7 +644,7 @@ def arc_ijk(self, target, center, plane, direction='CW', helix_len=None):
             raise RuntimeError("'center' must be a 2-tuple of numbers (passed %s)" % center)
 
         if plane == 'xy':
-            self.write('G17 {}XY plane'.format(self.comment_char))  # XY plane
+            self.write('G17 {}'.format(self._commentify('XY plane')))  # XY plane
             dims = {
                 'x' : target[0],
                 'y' : target[1],
@@ -592,7 +654,7 @@ def arc_ijk(self, target, center, plane, direction='CW', helix_len=None):
             if helix_len:
                 dims['z'] = helix_len
         elif plane == 'yz':
-            self.write('G19 {}YZ plane'.format(self.comment_char))  # YZ plane
+            self.write('G19 {}'.format(self._commentify('YZ plane')))  # YZ plane
             dims = {
                 'y' : target[0],
                 'z' : target[1],
@@ -602,7 +664,7 @@ def arc_ijk(self, target, center, plane, direction='CW', helix_len=None):
             if helix_len:
                 dims['x'] = helix_len
         elif plane == 'xz':
-            self.write('G18 {}XZ plane'.format(self.comment_char))  # XZ plane
+            self.write('G18 {}'.format(self._commentify('XZ plane')))  # XZ plane
             dims = {
                 'x' : target[0],
                 'z' : target[1],
@@ -756,8 +818,7 @@ def meander(self, x, y, spacing, start='LL', orientation='x', tail=False,
 
         actual_spacing = self._meander_spacing(minor, spacing)
         if abs(actual_spacing) != spacing:
-            msg = '{}WARNING! meander spacing updated from {} to {}'
-            self.write(msg.format(self.comment_char, spacing, actual_spacing))
+            self.write(self._commentify("WARNING! meander spacing updated from {} to {}".format(spacing, actual_spacing)))
         spacing = actual_spacing
         sign = 1
 
diff --git a/mecode/tests/test_main.py b/mecode/tests/test_main.py
index 69cc094..e2bc312 100755
--- a/mecode/tests/test_main.py
+++ b/mecode/tests/test_main.py
@@ -25,9 +25,9 @@ def setUp(self):
                    aerotech_include=False)
         self.expected = ""
         if self.g.is_relative:
-            self.expect_cmd('G91 ;relative')
+            self.expect_cmd('G91 ; relative')
         else:
-            self.expect_cmd('G90 ;absolute')
+            self.expect_cmd('G90 ; absolute')
 
     def tearDown(self):
         self.g.teardown()
@@ -68,10 +68,10 @@ def test_init(self):
     def test_set_home(self):
         g = self.g
         g.set_home()
-        self.expect_cmd('G92 ;set home')
+        self.expect_cmd('G92 ; set home')
         self.assert_output()
         g.set_home(x=10, y=20, A=5)
-        self.expect_cmd('G92 X10.000000 Y20.000000 A5.000000 ;set home')
+        self.expect_cmd('G92 X10.000000 Y20.000000 A5.000000 ; set home')
         self.assert_output()
         self.assert_position({'A': 5.0, 'x': 10.0, 'y': 20.0, 'z': 0})
         g.set_home(y=0)
@@ -79,16 +79,16 @@ def test_set_home(self):
 
     def test_reset_home(self):
         self.g.reset_home()
-        self.expect_cmd('G92.1 ;reset position to machine coordinates without moving')
+        self.expect_cmd('G92.1 ; reset position to machine coordinates without moving')
         self.assert_output()
 
     def test_relative(self):
         self.assertEqual(self.g.is_relative, True)
         self.g.absolute()
-        self.expect_cmd('G90 ;absolute')
+        self.expect_cmd('G90 ; absolute')
         self.g.relative()
         self.assertEqual(self.g.is_relative, True)
-        self.expect_cmd('G91 ;relative')
+        self.expect_cmd('G91 ; relative')
         self.assert_output()
         self.g.relative()
         self.assertEqual(self.g.is_relative, True)
@@ -97,7 +97,7 @@ def test_relative(self):
     def test_absolute(self):
         self.g.absolute()
         self.assertEqual(self.g.is_relative, False)
-        self.expect_cmd('G90 ;absolute')
+        self.expect_cmd('G90 ; absolute')
         self.assert_output()
         self.g.absolute()
         self.assertEqual(self.g.is_relative, False)
@@ -121,15 +121,15 @@ def test_setup(self):
         with open(os.path.join(HERE, '../header.txt')) as f:
             lines = f.read()
         self.expect_cmd(lines)
-        self.expect_cmd('G91 ;relative')
+        self.expect_cmd('G91 ; relative')
         self.assert_output()
 
     def test_home(self):
         self.g.home()
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G1 X0.000000 Y0.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 0, 'y': 0, 'z': 0})
@@ -150,9 +150,9 @@ def test_move(self):
 
         self.g.abs_move(20, 20, 0)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G1 X20.000000 Y20.000000 Z0.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
 
@@ -166,9 +166,9 @@ def test_move(self):
         self.assert_position({'x': 30.0, 'y': 30.0, 'z': 0.0, 'A': 50.0,
                                         'E': 0.45635101227893116})
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G1 X30.000000 Y30.000000 E0.456351
-        G91 ;relative
+        G91 ; relative
         """)
 
         self.assert_output()
@@ -202,9 +202,9 @@ def test_move(self):
         self.assert_position({'x': 40.0, 'y': 40.0, 'Z': 20, 'A':50, 'z':0.0,
                             'E': 1.4244176984302641})
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G1 E1.424418 Z20.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
 
@@ -221,27 +221,27 @@ def test_abs_move(self):
         self.g.relative()
         self.g.abs_move(10, 10)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G1 X10.000000 Y10.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 10, 'y': 10, 'z': 0})
 
         self.g.abs_move(5, 5, 5)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G1 X5.000000 Y5.000000 Z5.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 5, 'y': 5, 'z': 5})
 
         self.g.abs_move(15, 0, D=5)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G1 X15.000000 Y0.000000 D5.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 15, 'y': 0, 'D': 5, 'z': 5})
@@ -249,7 +249,7 @@ def test_abs_move(self):
         self.g.absolute()
         self.g.abs_move(19, 18, D=6)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G1 X19.000000 Y18.000000 D6.000000
         """)
         self.assert_output()
@@ -272,9 +272,9 @@ def test_rapid(self):
 
         self.g.abs_rapid(20, 20, 0)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G0 X20.000000 Y20.000000 Z0.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
 
@@ -289,27 +289,27 @@ def test_abs_rapid(self):
         self.g.relative()
         self.g.abs_rapid(10, 10)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G0 X10.000000 Y10.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 10, 'y': 10, 'z': 0})
 
         self.g.abs_rapid(5, 5, 5)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G0 X5.000000 Y5.000000 Z5.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 5, 'y': 5, 'z': 5})
 
         self.g.abs_rapid(15, 0, D=5)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G0 X15.000000 Y0.000000 D5.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 15, 'y': 0, 'D': 5, 'z': 5})
@@ -317,7 +317,7 @@ def test_abs_rapid(self):
         self.g.absolute()
         self.g.abs_rapid(19, 18, D=6)
         self.expect_cmd("""
-        G90 ;absolute
+        G90 ; absolute
         G0 X19.000000 Y18.000000 D6.000000
         """)
         self.assert_output()
@@ -330,7 +330,7 @@ def test_arc(self):
 
         self.g.arc(x=10, y=0)
         self.expect_cmd("""
-        G17 ;XY plane
+        G17 ; XY plane
         G2 X10.000000 Y0.000000 R5.000000
         """)
         self.assert_output()
@@ -338,8 +338,8 @@ def test_arc(self):
 
         self.g.arc(x=5, A=0, direction='CCW', radius=5)
         self.expect_cmd("""
-        G16 X Y A ;coordinate axis assignment
-        G18 ;XZ plane
+        G16 X Y A ; coordinate axis assignment
+        G18 ; XZ plane
         G3 X5.000000 A0.000000 R5.000000
         """)
         self.assert_output()
@@ -347,8 +347,8 @@ def test_arc(self):
 
         self.g.arc(x=0, y=10, helix_dim='D', helix_len=10)
         self.expect_cmd("""
-        G16 X Y D ;coordinate axis assignment
-        G17 ;XY plane
+        G16 X Y D ; coordinate axis assignment
+        G17 ; XY plane
         G2 X0.000000 Y10.000000 R5.000000 G1 D10
         """)
         self.assert_output()
@@ -356,8 +356,8 @@ def test_arc(self):
 
         self.g.arc(0, 10, helix_dim='D', helix_len=10)
         self.expect_cmd("""
-        G16 X Y D ;coordinate axis assignment
-        G17 ;XY plane
+        G16 X Y D ; coordinate axis assignment
+        G17 ; XY plane
         G2 X0.000000 Y10.000000 R5.000000 G1 D10
         """)
         self.assert_output()
@@ -370,20 +370,20 @@ def test_abs_arc(self):
         self.g.relative()
         self.g.abs_arc(x=0, y=10)
         self.expect_cmd("""
-        G90 ;absolute
-        G17 ;XY plane
+        G90 ; absolute
+        G17 ; XY plane
         G2 X0.000000 Y10.000000 R5.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 0, 'y': 10, 'z': 0})
 
         self.g.abs_arc(x=0, y=10)
         self.expect_cmd("""
-        G90 ;absolute
-        G17 ;XY plane
+        G90 ; absolute
+        G17 ; XY plane
         G2 X0.000000 Y10.000000 R0.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
         self.assert_position({'x': 0, 'y': 10, 'z': 0})
@@ -391,8 +391,8 @@ def test_abs_arc(self):
         self.g.absolute()
         self.g.abs_arc(x=0, y=20)
         self.expect_cmd("""
-        G90 ;absolute
-        G17 ;XY plane
+        G90 ; absolute
+        G17 ; XY plane
         G2 X0.000000 Y20.000000 R5.000000
         """)
         self.assert_output()
@@ -494,7 +494,7 @@ def test_meander(self):
 
         self.g.meander(2, 2, 1.1)
         self.expect_cmd("""
-        ;WARNING! meander spacing updated from 1.1 to 1.0
+        ; WARNING! meander spacing updated from 1.1 to 1.0
         G1 X2.000000
         G1 Y1.000000
         G1 X-2.000000
@@ -552,8 +552,8 @@ def test_meander(self):
         self.g.absolute()
         self.g.meander(3, 2, 1, start='LR', orientation='y')
         self.expect_cmd("""
-        G90 ;absolute
-        G91 ;relative
+        G90 ; absolute
+        G91 ; relative
         G1 Y2.000000
         G1 X-1.000000
         G1 Y-2.000000
@@ -561,7 +561,7 @@ def test_meander(self):
         G1 Y2.000000
         G1 X-1.000000
         G1 Y-2.000000
-        G90 ;absolute
+        G90 ; absolute
         """)
         self.assert_output()
         self.assert_position({'x': -3, 'y': 4, 'z': 0})
@@ -569,8 +569,8 @@ def test_meander(self):
     def test_clip(self):
         self.g.clip()
         self.expect_cmd("""
-        G16 X Y Z ;coordinate axis assignment
-        G18 ;XZ plane
+        G16 X Y Z ; coordinate axis assignment
+        G18 ; XZ plane
         G3 X0.000000 Z4.000000 R2.000000
         """)
         self.assert_output()
@@ -578,8 +578,8 @@ def test_clip(self):
 
         self.g.clip(axis='A', direction='-y', height=10)
         self.expect_cmd("""
-        G16 X Y A ;coordinate axis assignment
-        G19 ;YZ plane
+        G16 X Y A ; coordinate axis assignment
+        G19 ; YZ plane
         G2 Y0.000000 A10.000000 R5.000000
         """)
         self.assert_output()
@@ -587,8 +587,8 @@ def test_clip(self):
 
         self.g.clip(axis='A', direction='-y', height=-10)
         self.expect_cmd("""
-        G16 X Y A ;coordinate axis assignment
-        G19 ;YZ plane
+        G16 X Y A ; coordinate axis assignment
+        G19 ; YZ plane
         G3 Y0.000000 A-10.000000 R5.000000
         """)
         self.assert_output()
@@ -640,8 +640,8 @@ def test_rename_axis(self):
         self.assert_position({'x': 40.0, 'y': 30.0, 'z': 40, 'A': 10, 'B': 30,
                               'W': 10})
         self.expect_cmd("""
-        G16 X Y B ;coordinate axis assignment
-        G18 ;XZ plane
+        G16 X Y B ; coordinate axis assignment
+        G18 ; XZ plane
         G2 X10.000000 B10.000000 R7.071068
         """)
         self.assert_output()
@@ -650,11 +650,11 @@ def test_rename_axis(self):
         self.assert_position({'x': 0.0, 'y': 30.0, 'z': 0, 'A': 10, 'B': 0,
                               'W': 10})
         self.expect_cmd("""
-        G90 ;absolute
-        G16 X Y B ;coordinate axis assignment
-        G18 ;XZ plane
+        G90 ; absolute
+        G16 X Y B ; coordinate axis assignment
+        G18 ; XZ plane
         G2 X0.000000 B0.000000 R28.284271
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
 
@@ -722,11 +722,11 @@ def test_triangular_wave(self):
         self.g.absolute()
         self.g.triangular_wave(3, 2, 1, start='LR', orientation='y')
         self.expect_cmd("""
-        G90 ;absolute
-        G91 ;relative
+        G90 ; absolute
+        G91 ; relative
         G1 X3.000000 Y-2.000000
         G1 X-3.000000 Y-2.000000
-        G90 ;absolute
+        G90 ; absolute
         """)
         self.assert_output()
         self.assert_position({'x': 3, 'y': 4, 'z': 0})
diff --git a/mecode/tests/test_matrix.py b/mecode/tests/test_matrix.py
index 85e9a02..52464d4 100755
--- a/mecode/tests/test_matrix.py
+++ b/mecode/tests/test_matrix.py
@@ -90,12 +90,12 @@ def test_abs_zmove_with_flip(self):
         self.assert_almost_position({'x': 1.0, 'y': 0, 'z': 2})        
 
         self.expect_cmd("""
-        G90 ;absolute 
+        G90 ; absolute 
         G1 X-1.000000 Y0.000000 Z0.000000
-        G91 ;relative
-        G90 ;absolute 
+        G91 ; relative
+        G90 ; absolute 
         G1 X-1.000000 Y0.000000 Z2.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
 
@@ -106,12 +106,12 @@ def test_abs_zmove_with_rotate(self):
         self.g.abs_move(z=2)
         self.assert_almost_position({'x': 1.0, 'y': 0, 'z': 2})        
         self.expect_cmd("""
-        G90 ;absolute  
+        G90 ; absolute  
         G1 X0.000000 Y1.000000 Z0.000000
-        G91 ;relative
-        G90 ;absolute 
+        G91 ; relative
+        G90 ; absolute 
         G1 X0.000000 Y1.000000 Z2.000000
-        G91 ;relative
+        G91 ; relative
         """)
         self.assert_output()
 
@@ -128,7 +128,7 @@ def test_arc(self):
         self.g.rotate(math.pi/2)
         self.g.arc(x=10, y=0)
         self.expect_cmd("""
-        G17 ;XY plane
+        G17 ; XY plane
         G2 X0.000000 Y10.000000 R5.000000
         """)
         self.assert_output()        
@@ -139,7 +139,7 @@ def test_arc_reflect(self):
         self.g.arc(x=10,y=0)
         # Without the reflect this would be a G2.
         self.expect_cmd("""
-        G17 ;XY plane
+        G17 ; XY plane
         G3 X10.000000 Y0.000000 R5.000000
         """)
         self.assert_output()