FV: I assume that the registrations under the wing are to allow easy identification of the ULM should they (heaven forbid) ever be seen flying a bit low. In fact these underwing numbers are of giant size (maybe the large "14" you can see in your photo (post 1458) is part of its Calvados identity). But why the F-Jxxx is not displayed as for all other French light aircraft remains a mystery.
Laurence