You have to make a difference between an olympic triathlon to a non olympic one. Olympic triathlons rules are strict and clear. It's and olympic profession on all it's aspects. There are many, non olympic, different contests which cover more then one profession. These contests, sometimes called triathlons because they cover 3 professions, may have different rules according to the organizers. You'll be suprised and sometimes even amused how different can the rules get.