Thanks a lot Shanxi, to find me that explanation.
The people of the British Museum must certainly know what they write.
I thought of the
Roman Ioulian clan as a possibility.
IOULIEON is plural, so must count for the all clan (
Caesar until
Nero).
But finding this
legend on coins of Traian and
Antoninus Pius, who were no Ioulians, no Flavians but are counted under Adoptif Emperors and Antonine dynasty, I doubted that they would have such a
legend on their coins.
So, the British Museum says: yes, they do!
Thanks again!