They generally mean TAB 1 (unless specifically stating 1st fav ).
With commercial systems most are not worth the paper they are printed on though their are possibly 1 or 2 that may work for a short time (I might add A VERY SHORT TIME ).
Far better to purchase a couple of good racing books and learn to properly handicap a race rather than wasting money on systems .
Good luck with horse racing.
Cheers.
darky.