So what do you think the JUD is? And the three standards is what coin type? I am genuinely curious, not challenging what you believe....
Would it be an I rather than a J ? It was my understanding that emperors names such as JULIAN would be spelt IULIANVS or IOVIAN for Jovian etc?, so unlikely what you are seeing is a J? I am not at all certain on this for all coins though, someone will know more.