Taxation begins at the time of exercise. The bargain element of a non-qualified stock option is considered compensation and is taxed at ordinary income tax rates. For example, if an employee is granted 100 shares of Stock A at an exercise price of $25, the market value of the stock at the time of exercise is $50.
In the Internet Protocol version 4 (IPv4) [RFC791] there is a field called Protocol to identify the next level protocol. This is an 8 bit field. In Internet Protocol version 6 (IPv6) [RFC2460], this field is called the Next Header field. Values that are also IPv6 Extension Header Types should be listed in the IPv6 Extension Header Types registry at [IANA registry ipv6-parameters].
IPv6 is a new packet format that is not interoperable with the IPv4 packet format. The basic difference as others have said is that IPV4 is 32 bit and IPV6 is 128 bit. Think of IP addresses as normal physical addresses. Just like every computer has a unique MAC address or every house has an address. IP is a method of identifying source and destination nodes in a networking environment.