Keyboard apparatus free from incorrect fitting of key-top in type and fitting direction thereof

A keyboard apparatus comprising:

• a keyboard base;
• key-switch bodies arranged on said keyboard base;
• and
• key-tops corresponding to said key-switch bodies, each of said key-tops including a key-top side assortment cord having a first unique combination of convex portions and concave portions which is determined by a type of key-top thereof, and each of said key-switch bodies including a body side assortment cord having a second unique combination of convex portions and concave portions engageable wit the key-top side assortment cord,
• wherein said key-tops are fittable to said key-switch bodies only when the key-top side assortment cord is brought into engagement with the body side assortment cord, each of said key-tops further comprises a key-top side direction cord to define a fitting direction disposed in a different position from that of the key-top side assortment cord having one of a convex portion and a concave portion, and each of said key-switch bodies further comprises a body side direction cord disposed in an engaging position with the key-top side direction cord having one of a convex portion and a concave portion, and wherein said key-tops are fittable to said key-switch bodies only when the key-top side direction cord is brought into engagement with the body side direction cord.