Most IPv4 delegations correspond to a single "/prefix" address range.
A small percentage of IPv4 delegations correspond to several consecutive "/prefix" address ranges with the same holder, aggregated together in a single delegation (for example a /23 and the following /24 aggregated in a delegation with 768 addresses). In this case, colum "Prefix" is empty in the following delegations table, and the entry in the "IPv4 List" text file is represented with the format "First address;Number of addresses".