Update NXdetector_group.nxdl.xml

Aligned documentation with latest NXmx

base_classes/NXdetector_group.nxdl.xml

@@ -28,9 +28,9 @@
 	type="group" extends="NXobject">
 	<doc>
 		Logical grouping of detectors. When used, describes 
-		a group of NXdetectors.
+		a group of detectors.
 
-		Each detector is represented as a NXdetector 
+		Each detector is represented as an NXdetector 
 		with its own detector data array.  Each detector data array
 		may be further decomposed into array sections by use of
 		NXdetector_module groups.  Detectors can be grouped logically
@@ -57,25 +57,34 @@
 		 	group_parent:  [-1, 1, 1, 1, 1]
 	</doc>
 	<field name="group_names" type="NX_CHAR">
-	 	<doc>An array of the names of the detectors or the names of
-		hierarchical groupings of detectors.</doc>
+	 	<doc>
+			An array of the names of the detectors given in NXdetector
+			groups or the names of hierarchical groupings of detectors
+			given as names of NXdetector_group groups or in
+			NXdetector_group group_names and group_parent fields as
+			having children.
+
+			Specified in the base classes as comma separated list of names,
+			but new code should use an array of names as quoted strings.
+		</doc>
 	</field>
 	<field name="group_index" type="NX_INT">
 	 	<doc>
-	 	An array of unique indices for detectors or groupings
-		of detectors.
-						
-		Each ID is a unique ID for the corresponding detector or group
-		named in the field group_names.  The IDs are positive integers
-		starting with 1.nt. 
+			An array of unique indices for detectors or groupings 
+			of detectors.
+
+			Each ID is a unique ID for the corresponding detector or group
+			named in the field group_names.  The IDs are positive integers
+			starting with 1. 
 	 	</doc>
 		<dimensions><dim index="1" value="i"/></dimensions>
 	</field>
 	<field name="group_parent" type="NX_INT">
-	 	<doc>An array of the hierarchical levels of the parents of detectors
-		or groupings of detectors.
-
-		A top-level grouping has parent level -1.</doc>
+	 	<doc>
+			An array of the hierarchical levels of the parents of detectors
+			or groupings of detectors.
+
+			A top-level grouping has parent level -1.</doc>
 	    <dimensions><dim index="1" ref="group_index"/></dimensions>
 	</field>
 	<field name="group_type" type="NX_INT">