comments about seeking to switches

direct/src/doc/dcPacker.txt

@@ -125,6 +125,13 @@ pop() to unpack the nested elements of an array that you seek to.
     return;
   }
 
+To seek to a field nested within another structure, use a dot to
+compose the names: "parentName.fieldName".
+
+In unpack mode, you may seek to any field that has a name, including a
+field within the currently active case of a switch.  You may also seek
+to a switch parameter variable.  
+
 
 REPACK MODE (random write)
 
@@ -150,6 +157,13 @@ field with get_data() and get_length(), just as in pack mode.
 
   memcpy(result, packer.get_data(), packer.get_length());
 
+In repack mode, you may not traverse from beginning to end of the
+record--you must explicitly seek to each field you intend to repack.
+You may seek to a field within the currently active case of a switch.
+You may not seek directly to a switch parameter variable--repacking
+this would invalidate the remaining contents of the switch--but you
+may seek to the switch itself (if it has a name) and repack the entire
+contents of the switch at once.
 
 
 ADDITIONAL NOTES