As a matter of fact, an IPv6 address has a maximum (but not restricted)
fixed lenght of 64 bits for the network and subnetwork definition, and 64bit
for the interface identifier.
The most left 64 bit in that address contains information about type of
address, scope, network and subnetwork and another "useful" information.
But the fixed restricted lenght is not mandatory, and if locally managed
IPv6 addresses anre created, you can design routes via routing protocols to
follow the same rules as in CIDR.
Best regards xD.