Whenever a question arises, it is often best to go back to the source
document.

New Sporting Code (valid from October 1 2009, Declaration section:

4.2.1 Declaration content
a. Date of flight.
b. Name of the pilot-in-command, and the flight crew if any (see Annex C,
para 6.3c).
c. Glider type, and its registration or serial number or unique
NAC-assigned contest number.
d. The make, model and serial number of the FR used (as recorded in the
igc file for the flight). For any barograph or GPS position recorder
used, the make, model and serial
number as verified by the OO before flight.


Therefore the Competition number assigned by the SSA is perfectly good,
and most of this thread is irrelevant..............