FIRST POST!! Now seriously, there have been some discussion in the community on what it means the following sentence in the AGL Circuit Mod. Once per Round, players can re-roll any number of dice on a Roll where no Symbol has been obtained. Option a would mean that you could, once per round, reroll any blank result in a roll. Option b would mean that only rolls where no symbols have been obtained in all the dice can be rerolled, this would exclude Lunah's Called Shot, Wild Bill's Twin Pistols, among a few others with special symbols in their from being able to use this mod, since they have virtual dice with , , , and . Option c would be like option b, but allowing the aristos to reroll those blanks.
In the Spanish version, refers to the dice with no symbols, not the roll itself. "Una vez por Ronda, los Jugadores pueden repetir el lanzamiento de cualquier número de dados de una Tirada en los que no se haya obtenido ningún Símbolo"
My understanding of this mod is that once your rolled your dices, you take all of them that figured a blank side and roll them again. So combination of option A and C.