In IPv4, newborn LIRs must seek approval from the RIPE NCC before assigning a prefix larger than a certain size to end users.
As time goes (and RIPE see that you fill in the RIPE database correctly), this certain size increases upon being big enough for the LIR to assign IP addresses as it wishes.
This certain size is called an assignment window (AW) and is not a public information.
In order to gain approval from the RIPE NCC, LIRs willing to assign a prefix bigger than the AW must fill in the appropriate form. More information on AW can be found here.
Note also that trying to assign several small prefixes to overcome the AW will not work, as AW is valid over a 12 months period. (i.e. you can not assign more than a /XX to end user YYY in 12 months, without asking the RIPE first, neither in "one shot" nor via several smaller assignments.)
The actual question now : while this is perfectly clear for IPv4, I cannot find explicit references to the AW in the IPv6 Assignment and Allocation policy...
Does this mean that there is no AW in IPv6, or that the system is left unchanged (in that case, I cannot find the appropriate form) ?