Noun
an auxiliary activity
a line giving the name of the writer of a story or article
Source: WordNetby line
The reporter wrote with the hope that he would get a by-line in the Times, a testimony to his being alive on that day and all the tomorrows of microfilm. Gay Talese
As at The World, he used the by-line "G. Source: Internet
B.S.—as a by-line, and often signed himself "G. Source: Internet