More or less, yeah. Pronounced almost oh-juh, they are actually part of the Azurian religion and a large part of her culture. Their purpose is not ultra common knowledge in the human/siren lands, though it's not really a secret either. Most Azurei, when asked, are not forthcoming about them and will usually divert the subject. They serve both a religious purpose and a social one--ojih can be read by those who know the marks (almost exclusively Azurei, as they don't really teach the marks to others). This is important because Ridahne bears a mark that more or less explains what she's done and so now [I]everyone[/I] from her country knows just by looking at her. 

Ridahne did point out that mark to Darin and explained at one point that it marked her as an exile, so Darin would possibly have some guess as to what the tats are for.