File:Binomial distribution cdf.svg - Wikipedia, the free encyclopedia

This is pretty trivial but for the image on wiki of the CDF of a binomial distribution, why are there straight horizontal lines between each integer value? I thought that a binomial distribution is only defined for x values from 0, 1, 2, ...., n, but those horizontal lines indicate that a CDF value is also attached to non integer values between 0 and n? How is that possible? Shouldn't the CDF be just a single dot at each integer value of x?