Condo conversion refers to rental units being converted to condominiums. Typically not considered condo conversions are any rentals that were built and filed a condo map at that time, allowing use as condos later; usually done to avoid litigation regarding construction defects during the first 10 or 15 years after construction.
Mountain View has a unique condo conversion ordinance passed by voter initiative in 1979. It states that rentals cannot be converted (with a few exceptions) unless there are at least 15,373 rental units in the City. Since rental units have been approved in high numbers in the last few years, it is very unlikely that the number of rentals will ever fall below this threshold. More typical condo conversion ordinances tie conversions of rental units to the vacancy rate of apartments. Most common is a 5% vacancy rate over a period of time, as is used in Los Altos.