revert changes to application definitions without agreement

 * existing users may rely on the application defintions and not have code to deal with pixel positions
 * I assume canSAS is in agreement with the change
 * some white space changes

applications/NXcanSAS.nxdl.xml

@@ -893,7 +893,7 @@
             This is the x position where the direct beam would hit the detector plane.
             This is a length and can be outside of the actual
 	    detector.  The length can be in physical units or pixels
-	    as documented by the units attribute. The value can be any 
+	    as documented by the units attribute. The value can be any
             real number (positive, zero, or negative).
           </doc>
         </field>
@@ -903,8 +903,9 @@
             Position of the beam center on the detector.
 
             This is the y position where the direct beam would hit the detector plane.
-            This is a length and can be outside of the actual detector.  The length can be in physical units or pixels
-	    as documented by the units attribute. The value can any 
+            This is a length and can be outside of the actual
+	    detector.  The length can be in physical units or pixels
+	    as documented by the units attribute. The value can be any
             real number (positive, zero, or negative).
           </doc>
         </field>

applications/NXmx.nxdl.xml

@@ -2,9 +2,9 @@
 <?xml-stylesheet type="text/xsl" href="nxdlformat.xsl" ?>
 <!--
   # NeXus - Neutron and X-ray Common Data Format
-  # 
+  #
   # Copyright (C) 2013-2017 NeXus International Advisory Committee (NIAC)
-  # 
+  #
   # This library is free software; you can redistribute it and/or
   # modify it under the terms of the GNU Lesser General Public
   # License as published by the Free Software Foundation; either
@@ -36,7 +36,7 @@
 				These symbols will be used below to coordinate datasets
 				with the same shape.  Most MX x-ray detectors will produce
 				two-dimensional images.  Some will produce three-dimensional
-				images, using one of the indices to select a detector element. 
+				images, using one of the indices to select a detector element.
 			</doc>
 			<symbol name="dataRank">
 				<doc>rank of the ``data`` field</doc>
@@ -94,10 +94,10 @@
 					in the field group_index, and the level in the hierarchy
 					given in the group_parent field.  For example if an x-ray
 					detector, DET, consists of four elements in a rectangular array::
-							 
+
 							 DTL	DTR
 							 DLL	DLR
-							 
+
 					We could have::
 
 						 group_names: ["DET", "DTL", "DTR", "DLL", "DLR"]
@@ -143,7 +143,7 @@
 					<doc>
 						Normally the detector group will have the name ``detector``.
 						However, in the case of multiple detector elements, each element
-						needs a uniquely named NXdetector group. 
+						needs a uniquely named NXdetector group.
 					</doc>
 					<field name="depends_on" type="NX_CHAR" /> <!-- better type for paths needed  -->
 
@@ -200,7 +200,7 @@
 							data for this module.  If the module is associated with
 							a full data array, rather than with a hyperslab within
 							a larger array, then a single module should be defined,
-							spanning the entire array. 
+							spanning the entire array.
 						</doc>
 						<field name="data_origin" type="NX_INT">
 							<doc>
@@ -216,15 +216,15 @@
 						</field>
 						<field name="data_size" type="NX_INT">
 							<doc>
-								Two or three values for the size of the module in pixels in 
+								Two or three values for the size of the module in pixels in
 								each direction.
 							</doc>
 						</field>
 						<field name="data_stride" type="NX_INT" minOccurs="0">
 							<doc>
-								Two or three values for the stride of the module in pixels in 
+								Two or three values for the stride of the module in pixels in
 								each direction.  By default the stride is [1,1] or [1,1,1],
-								and this is the most likely case.  This optional field is 
+								and this is the most likely case.  This optional field is
 								included for completeness.
 							</doc>
 						</field>
@@ -308,19 +308,19 @@
 						minOccurs="0">
 						<doc>
 							This is the x position where the direct beam would hit the
-							detector. This is a length and can be outside of the actual 
-							detector. The length can be in physical units or pixels
-	    as documented by the units attribute.
+							detector. This is a length and can be outside of the actual
+							detector. The length can be in physical units or pixels as
+							documented by the units attribute.
 						</doc>
 					</field>
 
 					<field name="beam_center_y" type="NX_FLOAT" units="NX_LENGTH"
 						minOccurs="0">
 						<doc>
 							This is the y position where the direct beam would hit the
-							detector. This is a length and can be outside of the actual 
-							detector. The length can be in physical units or pixels
-	    as documented by the units attribute.
+							detector. This is a length and can be outside of the actual
+							detector. The length can be in physical units or pixels as
+							documented by the units attribute.
 						</doc>
 					</field>
 
@@ -527,7 +527,7 @@
 						single shot exposures.
 
 						Use of the depends_on field and the NXtransformations group is
-						strongly recommended.  As noted above this should be an absolute 
+						strongly recommended.  As noted above this should be an absolute
 						requirement to have for any scan experiment.
 
 						The reason it is optional is mainly to accommodate XFEL
@@ -553,7 +553,7 @@
 					<field name="incident_wavelength_weight" type="NX_FLOAT" minOccurs="0" >
 						<doc>
 							In the case of a polychromatic beam this is an array of the
-							relative weights of the corresponding wavelengths in 
+							relative weights of the corresponding wavelengths in
 							incident_wavelength.
 						</doc>
 					</field>
@@ -585,7 +585,7 @@
 					<field name="incident_beam_size" type="NX_FLOAT" units="NX_LENGTH"  minOccurs="0">
 						<doc>
 							Two-element array of FWHM (if Gaussian or Airy function) or
-							diameters (if top hat) or widths (if rectangular) of beam 
+							diameters (if top hat) or widths (if rectangular) of beam
 							in the order x, y
 						</doc>
 						<dimensions rank="1" value="2" />

applications/NXsas.nxdl.xml

@@ -129,17 +129,13 @@
 		<field name="beam_center_x" type="NX_FLOAT" units="NX_LENGTH">
 			<doc>
 				This is the x position where the direct beam would hit the detector. This is a
-				length and can be outside of the
-				actual detector. The length can be in physical units or pixels
-	    as documented by the units attribute.
+				length not a pixel position and can be outside of the actual detector.
 			</doc>
 		</field>
         <field name="beam_center_y" type="NX_FLOAT" units="NX_LENGTH">
 			<doc>
 				This is the y position where the direct beam would hit the detector. This is a
-				length and can be outside of the
-				actual detector. The length can be in physical units or pixels
-	    as documented by the units attribute.
+				length not a pixel position and can be outside of the actual detector.
 			</doc>
 		</field>
       </group>

applications/NXsastof.nxdl.xml

@@ -114,17 +114,13 @@
         <field name="beam_center_x" type="NX_FLOAT" units="NX_LENGTH">
                <doc>
 	               This is the x position where the direct beam would hit the detector. This is a
-	               length and can be outside of the actual
-		       detector. The length can be in physical units or pixels
-	    as documented by the units attribute.
+	               length not a pixel size and can be outside of the actual detector.
                </doc>
         </field>
         <field name="beam_center_y" type="NX_FLOAT" units="NX_LENGTH">
                  <doc>
-	                 This is the y position where the direct beam would hit the detector. This is a
-	                 length and can be outside of the actual
-			 detector. The length can be in physical units or pixels
-	    as documented by the units attribute.
+	               This is the y position where the direct beam would hit the detector. This is a
+	               length not a pixel size and can be outside of the actual detector.
                  </doc>
        </field>
       </group>

applications/NXxrot.nxdl.xml

@@ -50,15 +50,15 @@
           <field name="beam_center_x" type="NX_FLOAT" units="NX_LENGTH">
            <doc>
               This is the x position where the direct beam would hit the detector. This is a
-              length and can be outside of the actual detector. The length can be in physical units or pixels
-	    as documented by the units attribute.
-            </doc></field>
+              length not a pixel position and can be outside of the actual detector.
+            </doc>
+           </field>
         <field name="beam_center_y" type="NX_FLOAT" units="NX_LENGTH">
             <doc>
-                This is the y position where the direct beam would hit the detector. This is a
-                length and can be outside of the actual detector. The length can be in physical units or pixels
-	    as documented by the units attribute.
-        </doc></field>        
+              This is the y position where the direct beam would hit the detector. This is a
+              length not a pixel position and can be outside of the actual detector.
+            </doc>
+        </field>
       </group>
       <group type="NXattenuator" name="attenuator">
         <field name="attenuator_transmission" type="NX_FLOAT"