(TeX-add-style-hook "_region_"
 (lambda ()
    (LaTeX-add-environments
     "ex")
    (TeX-add-symbols
     '("sheettitle" 3)
     "makesheettitle"
     "exheader"
     "labelenumitemp")
    (TeX-run-style-hooks
     "typearea"
     "hyperref"
     "helvet"
     "totpages"
     "scrpage2"
     "ifthen"
     "calc"
     "amsfonts"
     "amsmath")))