 Additional nomenclature , in the form of lower @-@ case letters added to the end of the spectral type to indicate peculiar features of the spectrum . For example , an " e " can indicate the presence of emission lines ; " m " represents unusually strong levels of metals , and " var " can mean variations in the spectral type . 
 Additional nomenclature , in the form of lower @-@ case letters added to the end of the spectral type to indicate peculiar features of the spectrum . For example , an " e " can indicate the presence of emission lines ; " m " <a href='uninflect' title='1'><mark>represents</mark></a> unusually strong levels of metals , and " var " can mean variations in the spectral type . 
Additional nomenclature , in the form of lower @-@ case letters added to the end of da spectral type to indicate peculiar features of tdaspectrum . For example , an " e " can indicate thdaresence of emission lines ; " m " represent unusually strong levels of metals , and " var " can mean variations in the spectral type .