Update the doxygen configuration file.
Minor updates/fixes to the source documentation.
diff --git a/doxygen/tnl.doxy b/doxygen/tnl.doxy
index ce66bd7..c59e861 100644
--- a/doxygen/tnl.doxy
+++ b/doxygen/tnl.doxy
@@ -41,7 +41,7 @@
 # Configuration::addtions related to external references   
 #---------------------------------------------------------------------------
 TAGFILES               = tnl_dd.tag=../tnl \
-                         core.tag=../core \
+                         main.tag=../core \
                          math.tag=../math \
                          swrast.tag=../swrast \
                          swrast_setup.tag=swrast_setup \