600 Subfield $x - General subdivision:

Subfield $x contains a subject subdivision that is not more appropriately contained in subfields $v (Form subdivision) , $y (Chronological subdivision) , or $z (Geographic subdivision) . Subfield $x is appropriate only when a general subdivision topical is added to a name or a name/title.

Examples:

600 10$aBrunhoff, Jean de,$d1899-1937$xCharacters$xBabar.

600 00$aNapoleon$bI,$cEmperor of the French,$d1769-1821$xAssassination attempt, 1800 (December 24)