It's not "omit zeroes". It's, "represent the last three octets with just one integer". 127.256 is valid, and would be equivalent to 127.0.1.0. The last integer

It's not "omit zeroes". It's, "represent the last three octets with just one integer". 127.256 is valid, and would be equivalent to 127.0.1.0. The last integer can be up to 16777215 (2²⁴-1). Similarly, if you instead include three groups of integers, the first two represents one octet each, and the last represents two. 127.2.256 is equivalent to 127.2.1.0.