The K-type was proposed by J. F. Bell and colleagues in 1988 for bodies having a particularly shallow 1 μm absorption feature, and lacking the 2 μm absorption.
Trieda K-typov bola navrhnutá a vytvorená v roku 1988 J. F. Bellom, ako trieda pre všetky telesá, ktoré majú slabú 1 μm absorpciu a chýbajúcu 2 μm absorpciu.