STR - Starter Allowance Starter allowance races are identical to starter handicap races with the only difference that horses competing in this race are weighted through allowance conditions (i.e. number of races or money won).
SHP - Starter Handicap This category is reserved for horses that have been running in inferior claiming company, but have improved to the point that they would not be risked being sold in a claiming race. In effect this race is an allowance race restricted to horses that have previously run in a claiming race at a specific level (e.g. starters for a claiming price of $5,000). In a starter handicap race, horses are weighted similar to a handicap race.
AOC (also known as Optional Claiming or OC) This race type is quite involved and incorporates features of starter allowance and claiming races. Horses competing in this type of race can either compete as a claimer, or as a starter allowance horse, with no claiming price. Those competing in this race that are not eligible to be claimed must have competed at or below the claiming level specified, and have not won a race at the specified claiming or higher since last competing at the specified claiming level or a lower claiming price.
SOC - Starter Optional Claiming This race is a combination of a Starter Allowance and Claiming race. The basic condition is that the horse has raced within a given time past in a Claiming race with a stated price of "X" dollars or less. Horses can enter with a claiming price or without.
Maiden Race, as you know, is a race for horses who have not won a race. They can be classified as Maiden Special Weight (MSW) or Maiden Claiming (MCL).