OBA

[JayTownsend]

>The official answer is that you can fire up to 3 OBA allottments at one (and only one) target hex.

That is correct! You also fire at separate targets besides being grouped together for one hex. Rule 9.2: Unless scenario instructions say otherwise, EACH offboard artillery factor available in a scenario my fire once per turn at ANY hex on the board containing spotted unit(s) (it has unlimited range).

See example under rule 9.3:

Example: The scenario instructions give the American player an OFF-map artillery value of "3 x 20." These may be combined into one 60-value bombardment, one 40 and one of 20, or three separate bombardmants of 20. They may not be combined with any ON-board units.