Index: trunk/BNC/bnchelp.html
===================================================================
--- trunk/BNC/bnchelp.html	(revision 1881)
+++ trunk/BNC/bnchelp.html	(revision 1885)
@@ -413,11 +413,12 @@
 </p>
 
-<p><a name="corrdir"><h4>3.6.1 Directory - optional</h4></p>
-<p>
-Specify a directory for saving Broadcast Corrections in files. If the specified directory does not exist, BNC will not create Broadcast Correction files. Default value for Broadcast Corrections 'Directory' is an empty option field, meaning that no Broadcast Correction files will be created.
-</p>
-<p>
-The file name convention for Broadcast Correction files follows the convention for RINEX files except for the last character of the file name suffix which is set to "C".
-</p>
+<p>
+Orbit corrections are provided in along-track, cross-track and radial components. The along-track component is parallel to the velocity vector, the cross-track component is perpendicular to the plane of motion and the radial component is perpendicular to both along-track and cross-track components. The three components form an orthogonal system in WGS-84.
+</p>
+
+<p>
+Broadcast Corrrections can be saved by BNC in files. The file name convention for Broadcast Correction files follows the convention for RINEX files except for the last character of the file name suffix which is set to "C".
+</p>
+
 <p>
 The saved files contain parameters in plain ASCII format. The first five parameters in each record are:
@@ -555,4 +556,9 @@
 ...
 </pre>
+
+<p><a name="corrdir"><h4>3.6.1 Directory - optional</h4></p>
+<p>
+Specify a directory for saving Broadcast Corrections in files. If the specified directory does not exist, BNC will not create Broadcast Correction files. Default value for Broadcast Corrections 'Directory' is an empty option field, meaning that no Broadcast Correction files will be created.
+</p>
 
 <p><a name="corrint"><h4>3.6.2 Interval - mandatory if 'Directory' is set</h4></p>