2. Investment method, also known as hardcore. Used for most commercial (and residential) property that is producing future cash flows through the letting of the property. This method compares the estimated rental value (ERV), or "top slice" to the current ("passing") income, or "bottom slice", to give an indication of whether the future value of the property should rise or fall based on income. If a property's income is higher than the ERV this is sometimes known as "froth", which may be confused with the US use of "froth" describing the period before a real estate bubble.