That's because "ARIN, RIPE NCC, APNIC, AfriNIC, LACNIC" are names of organizations, not technical terms.
The very first line has enough information to know what it does:
"A tool to enumerate CIDRs by querying RIRs & BGP ASN prefix lookups"
In other words, it queries two sources (regional Internet registries -- the organizations referred to above -- and information from the BGP protocol) to enumerate blocks of IP addresses.
The very first line has enough information to know what it does:
"A tool to enumerate CIDRs by querying RIRs & BGP ASN prefix lookups"
In other words, it queries two sources (regional Internet registries -- the organizations referred to above -- and information from the BGP protocol) to enumerate blocks of IP addresses.