Varies depending on the address form but could contain hexadecimals, decimals 0 through 255, and double colons (::).

See IPv6 Address Representation later in this section for more information.

A 128-bit (16-byte) number that includes a network prefix and an interface identifier. The interface identifier must be unique within the link. The nodes of an IPv6 address are separated by colons (:). The link-local identifier must be unique within the link. The nodes of an IPv6 address are separated by colons.

IPv6 addresses are 128-bit identifiers for interfaces and sets of interfaces.

Fields in IPv6 addresses are given a specific name, for example, "subnet." When this name is used with the term "ID" after the name (for example, "subnet ID"), it refers to the contents of the named field. When this name is used with the term "prefix" (for example, "subnet prefix"), it refers to all of the address from the left up to and including this field.

In IPv6, 0 (zero) and 1 are legal values for any field, unless specifically excluded. Specifically, prefixes can contain or end with zero-valued fields.