+dnl disable external effects in XML
+dnl -------------------------------
+AC_MSG_CHECKING([for using external effects in xml2])
+AC_ARG_ENABLE(external-effects,
+[ --disable-external-effects disable descriptions of external effects in XML],
+[if test "$enableval"="no"; then
+ enable_external_effects=no
+fi],
+[enable_external_effects=yes])
+AC_SUBST(enable_external_effects)
+if test "$enable_external_effects" == no; then
+ AC_MSG_RESULT([disabled])
+else
+ AC_MSG_RESULT([enabled])
+fi
+dnl check for header and library below
+