better comments

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/thdata@35 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
1.0-6

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/thdata@36 edb9625f-4e0d-4859-8d74-9fd3b1da38cb