There are no special rules: the designs are described differently in each type of literature, and the crests of the imperial families are indicated in details with the number of petals and the unit of petals and leaves (e.g. sixteen petals (edict of Dajokan (Grand Council of state)/Jurokuyo (sixteen leaves (Koshitsurei (the Imperial Families' Act)).
特に決まりはなく、文献により表現の仕方が違い、とりわけ皇室・皇族関係の紋には、詳しく花びらの数に弁や葉（十六弁（太政官布告）・十六葉（皇室令））などの単位がつけられることがある。