How do I request Internet number resources?
You will have to send us documentation that proves the technical need for any Internet number resources that you request.
Quantities of address space are now referred to by their prefix length (or subnet mask). For example, /24 refers to 256 IP addresses, the equivalent of a former Class C. /19 refers to 8,192 IP addresses, the equivalent of 32 former Class Cs.
See also: Understanding IP Addressing