cd18d7a2_logue_Format___Stellarium_Wiki_Star_Data_Record_Type_0_Description
[Name] sp_int [Offset] 11 [Type] unsigned short int [Size] 2 [Description] 
This is the index in an array of spectral type descriptions which is taken from the file stars_hip_sp.cat, the index corresponds to the line number in the file - 1
Star Catalogue Format - Stellarium Wiki