When a pair is newly formed (because of injury or a newly formed partnership), the new pair may be composed of two strong players who, in all likelihood, would achieve a high World Ranking once they have played together for some time.
Notional ranking is a method to estimate the strength of such newly formed pairs, and to seed them when appropriate.
The pre-requisite for having a Notional Ranking is that at least one player in the pair must have played with different partners during the 52 weeks period prior to the seeding date.
The explanation of adjusted and notional rankings can be found in Appendix 7 of the General Competition Regulations.
Referees may also use the Notional Ranking Calculator.