"co" is also frequently used as a second-level domain within other country-code domains, in which registrants (usually companies) may register second-level domains of the form .co.xx, where xx is the ccTLD. Israel (.co.il), United Kingdom (.co.uk), New Zealand (.co.nz), Japan (.co.jp), South Korea (.co.kr) and Cook Islands (.co.ck) are examples. Some other country codes use "com" instead, such as Australia (.com.au), Mexico (.com.mx) and Taiwan (.com.tw); this includes Colombia itself, which uses .com.co.
Around the year 2000 when many country-code domains were being remarketed as worldwide generic domains, there was some talk of allowing second-level registrations in .co for registrants worldwide in order to capitalize on the similarity of this name to .com and to the above-noted use of "co" as a second-level domain in other country codes. However, a Court order prohibited Andes University from doing so, and registration remains limited to third-level domains and to Colombian registrants.
The second-level domain structure rather closely mirrors the "traditional IANA" .com / .net / .org / .gov / .edu / .mil hierarchy, with the addition of a national equivalent of .name