The scripting language can handle 32bit values in most features and double values in calculations, such as in $calc(). It cannot handle 64bit values or larger. An IPv6 address is a 128bit value. While it would be possible to update $longip() to return a 128bit value in this specific case, the result would be unusable anywhere else in the scripting language. This means that if you need to manipulate 128bit values, you will need to write your own methods to do this.
