Output who -l some columns unknown

Today another day of studying: who turn I type who -l who -l UUCP . Feb 22 15:57 0:14 488 LOGIN console Feb 22 15:57 0:07 494 zsmon . Feb 22 15:57 0:14 495 LOGIN console Feb 22 16:03 0:07 1011 (:0) first column is the name of line (ttymon) second is tty used third date of creation the fourth column? (488, 494, 1011..)