This type falls in the category of structured products
with capital protection.
On the expiration date the investor will receive full or partial return of the certificate face value (90-100% of par depending on bond prospectus terms), and the income if the underlying asset grows higher of its original value. If the structured product is oriented to the fall of the underlying asset value, the investor will have income in case the underlying asset gets lower than its original value. The farther the price goes in the desired direction, the higher is the income. If the expectations on the changes in the underlying asset price are not met, the investor gets no income.