site-local address - Address that is useful only in the context of the site and is similar to the private addresses in IPv4. Its scope is limited to this context. When configured, a site-local address uses a specific prefix (FEC0::/10) and concatenates the subnet ID as a 16-bit field and then the interface ID in the modified EUI-64 format. See also anycast address, global unicast address, IPv6 multicast address, link-local address, and solicited-node multicast address.
How can I manage to force the hex decimal "FEC0" within the limit of 10 bits ?
An Internet Protocol (IP) address is a numerical identification and logical address that is assigned to devices participating in a computer network utilizing the Internet Protocol for communication between its nodes. Although IP addresses are stored as binary numbers, they are usually displayed in human-readable notations, such as 18.104.22.168 (for IPv4), and 2001:db8:0:1234:0:567:1:1 (for IPv6). The role of the IP address has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."