I was reviewing the language of a mechirat chametz contract I had been sent and noticed some unusual specific language defining the parameters of the sale:

...The term 'Chometz' shall refer to any of the five grains which are wheat, barley, rye ,oats and spelt which have become fermented or partially fermented in any form or amount whatsoever;

The term 'Sior' shall refer to any one of the above mentioned grains

that are able to produce fermenation, such as yeast;

The above-mentioned 'Chometz' or 'Sior' includes any solid or liquid substances which are edible or partially edible to a human being or even to a canine, such as but not limited to:breads, starches, alcoholic beverages, vinegar,cosmetics,medicines,vitamins,grocery products, animal foods and any substance or substances that contain even a minute amount or derivative of Chometz' or Sior'or had acquired a taste of 'Chometz' or 'Sior' by being cooked with 'Chometz' or 'Sior'or being cooked with or stored in utensils that have been used with 'Chometz' or 'Sior'...

Considering that, for example, even matzoh may have some fermentation, even if it doesn't reach the halachic shiur (significant amount) of surface cracks forming, shouldn't the contract be assumed to effect a sale of even non-chametz products, potentially resulting in acts of theft on the part of the seller from the buyer over the course of the holiday, whenever seller uses these slightly fermented products? Is there a halachic basis to assume that "fermentation" is assumed to only mean halachic "chimutz" and/or that the products being sold are only the ones intended, e.g. based on general convention?