diff --git a/examples/MVLinac/FullTxHeadField.txt b/examples/MVLinac/FullTxHeadField.txt
index 41c5ad0..3d26254 100644
--- a/examples/MVLinac/FullTxHeadField.txt
+++ b/examples/MVLinac/FullTxHeadField.txt
@@ -1,5 +1,5 @@
-# FullTxHeadField.txt contains parameter values for a specific source and geometry
-# in this example, a 6 MV Siemens Oncor x-ray beam.
+# FullTxHead.txt contains parameter values for a specific source and geometry. In this 
+# example, a 6 MV Siemens Oncor x-ray beam.
 #
 # The parameters settings in this file override parameter settings in the files in the
 # includeFile statement below and in LinacDefaults.txt.
@@ -26,12 +26,14 @@
 # ^IEC_G/RotY_G: IEC gantry rotation angle
 # ^IEC_B/RotZ_B: IEC secondary collimator (jaw and MLC) rotation angle
 # ^IEC_S/RotZ_S: IEC Patient Couch rotation angle
+# Jaw/RotZ: Jaw orientation, dependent on direction of jaw travel along IEC_B
+# MLC/RotZ: MLC orientation, dependent on direction of leaf travel along IEC_B
 # ^Pos: Distance along beam axis Zg from nominal target position (SAD from isocenter)
 # TransZ: Position of center of object along Zg
 # JawTravelAxis: Direction of jaw travel, along IEC_B axis Xb or Yb
 # LeafTravelAxis: Direction of leaf travel, along IEC_B axis Xb or Yb
-# ^NegativeFieldSetting: Jaw or MLC leaf position on negative side, projected to isocenter
-# ^PositiveFieldSetting: Jaw or MLC leaf position on positive side, projected to isocenter
+# ^NegativeFieldSetting: Jaw or MLC leaf position on negative side (IEC X1), projected to isocenter
+# ^PositiveFieldSetting: Jaw or MLC leaf position on positive side (IEC X2),  projected to isocenter
 # LeafWidths: Width of each leaf as projected to isocenter, same width on opposing bank
 ######################################################################################
 
@@ -88,24 +90,26 @@ includeFile = Jaws.txt MLC.txt WaterBox.txt
 dc:Ge/IEC_G/RotY_G                           = 0. deg
 d:Ge/IEC_G/RotY                              = -1 * Ge/IEC_G/RotY_G deg
 
-# IEC collimator rotation angle (in the same sense of RotZ)
+# IEC collimator rotation angle (in the opposite sense of RotZ)
 dc:Ge/IEC_B/RotZ_B                           = 0. deg
-d:Ge/IEC_B/RotZ                              = 1 * Ge/IEC_B/RotZ_B deg 
+d:Ge/IEC_B/RotZ                              = -1 * Ge/IEC_B/RotZ_B deg 
 
 # Asymmetric jaw field settings along IEC coordinates X or Y, projected to isocenter
-s:Ge/Jaw/JawTravelAxis                       = "Y" # Jaw travel axis, "X" or "Y"
-dc:Ge/Jaw/NegativeFieldSetting               = -5. cm
-dc:Ge/Jaw/PositiveFieldSetting               = 5. cm
-
-# MLC leaf widths and positions, projected to isocenter
-s:Ge/MLC/LeafTravelAxis                      = "X" # Leaf travel axis, "X" or "Y"
+# Default 20 cm wide field at plane of isocenter (at SAD)
+dc:Ge/Jaw/NegativeFieldSetting  = -10 cm #Field setting along negative IEC_B axis
+dc:Ge/Jaw/PositiveFieldSetting  = 10 cm #Field setting along positive IEC_B axis
+d:Ge/Jaw/RotZ = Ge/Jaw/JawRotZforTravelAlongIECX deg # Set to JawRotZforTravelAlongIECX or JawRotZforTravelAlongIECY
+
+# MLC orientation, leaf widths and positions, projected to isocenter
+# Default 20 cm wide, 50 cm long field at plane of isocenter (at SAD) with all leaves open
+d:Ge/MLC/RotZ = Ge/MLC/MLCRotZforTravelAlongIECY deg # Set to MLCRotZforTravelAlongIECX or MLCRotZforTravelAlongIECY
+# MLC orientation, leaf widths and positions, projected to isocenter for 20 cm x 50 cm field
+# IEC leaf number depends on direction of leaf motion: For Xb leaf 1 is first, Yb leaf 1 is last
 dv:Ge/MLC/LeafWidths           = 42 5. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 5. cm
-# 10 cm x 20 cm field, the field setting for each leaf is that as projected at isocenter
-dv:Ge/MLC/NegativeFieldSetting = 42 0. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. -5. 0. cm
-dv:Ge/MLC/PositiveFieldSetting = 42 0. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 5. 0. cm
+dv:Ge/MLC/NegativeFieldSetting = 42 -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. -10. cm
+dv:Ge/MLC/PositiveFieldSetting = 42 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. 10. cm
 
 # Patient and couch field-dependent components
 # IEC couch rotation angle (in the opposite sense of RotZ)
 dc:Ge/IEC_S/RotZ_S                           = 0.0 deg
 d:Ge/IEC_S/RotZ                              = -1 * Ge/IEC_S/RotZ_S deg
-