abstract Examples = {

flags startcat = Ex ;

cat
  Ex ;
fun 
  ex01, ex02, ex04, ex08, ex13, ex19, ex20, ex23,
  ex03, ex05, ex06, ex07, ex10, ex12, ex14, ex15, ex16, ex24, ex25, ex26, ex27,
  ex09,
  ex11, ex17, ex18, ex21, ex22 : Ex ;
}