The Id (process name) is a unique sequence of 1-4 characters which identifies an entry in inittab file (for versions of sysvinit compiled with libraries < 5.2.18 or a.out libraries the limit is 2 characters).
Note: For gettys or other login processes, the field should be the tty suffix of the corresponding tty, e.g.1 for tty1. Otherwise, the login accounting might not work correctly.