system_chart THE_WORLD
  cluster EARTH description "A small, insignificant planet."
end

cluster_chart EARTH
  class CITIZEN description "A humanoid."
  class NOBLEPERSON description "A rich humanoid."
end

class_chart CITIZEN
indexing
  clauster: "CIVIL_STATUS " ;
  created: "1993-03-15 jmn";
  revised: "1993-05-12 kw";
explanation
  "Person born or living in a country"
part "1/1 "
query
  "Name", "Sex", "Age", "Single", "Spouse", "Children", "Parents",
  "Impediment to marriage"
command
  "Marry", "Divorce"
constraint
  "Each citizen has two parents.",
  "At most one spouse allowed.",
  "May not marry children or parents or person of same sex.",
  "Spouse's spouse must be this person.",
  "All children, if any, must have this person among their parents."
end

class_chart NOBLEPERSON
indexing
  cluaster: "CIVIL_STATUS" ;
  created: "1993-03-15 jmn";
  revised: "1993-05-12 kw", "1993-12-10 kw"
explanation
  "Person of noble rank"
part "1/1 "
inherit CITIZEN
query
  "Assets", "Butler"
constraint
  "Enough property for independence.",
  "Can only marry other noble person.",
  "Wedding celebrated with style.",
  "Married nobility share their assets and must have a butler."
end