There's no visa (as in "visability") needed for a codeshare.



On a serious note, this flight is not sold point to point (they don't have the rights to do so), so it's inhibited on the point-to-point availability, but will be used for building connections. AA reservations or a travel agent can book it point to point by longsell (not on AA.com).

Finally, the PRS (pre-reserved seating) rules for BA are the same whether you book it as BA or as codeshare.