3e255347_logue_Format___Stellarium_Wiki_Star_Data_Record_Type_0_Type
[Name] component_ids [Offset] 3 [Size] 1 [Description] This is an index to an array of catalogue number suffixes. The list is read from the stars_hip_component_ids.cat file. The value of this field turns out to be the line number in the file - 1 [Type] 
unsigned char
i n t
u n s i g n e d c h a r
u n s i g n e d s h o r t i n t
Star Catalogue Format - Stellarium Wiki