Note on MK  : Explanation of the Classification Terminology (from Table 1): (standard) Classification standard star s Sharp lined n Broad lined nn Very broad lined ksn The Ca II K line has both sharp and broad components st Strong wk Weak v. Very Lam Boo A star in which many of the metals are weak,
indicating underabundances
4481 weak The 4481 Mg II line is weak. Measures may
indicate that other lines are also weak. This may be a mild version of the Lambda Boo stars.
Am(A3/A7/F0) A metallic line star in which the spectral
type based on the Ca II K line is A3, on the Balmer lines is A7, and on the metallic lines is F0. This is an abbreviation of the form Am(K/H/M=A3/A7/F0).
p(SrEuCr st, CaMg wk) An Ap star in which the Sr is strongest
relative to the standards, Eu is next strongest, etc.; the lines of Ca and Mg are weak relative to those in standards. The type is based on the hydrogen lines.
shell(Ti,Ca) A shell spectrum that has sharp Ti and Ca
absorption lines.
(:) Uncertainty in the previous symbol.