How to “decipher” the symbol for the recently announced doubly-charmed baryon?

The name of the particle (resonance?) in the recent announcement Observation of the doubly charmed baryon $\Xi^{++}_{cc}$ is complicated. I'm sure it's standard notation but I don't know how to "decode" it.

Is it possible to explain the Xi and the two super-scripts and subscripts? A short description would be fine. I'm wondering if the two plus signs indicate a double charge or isospin or something else, but I'm guessing that the double c's are related to "doubly charmed" in the title.

• – user154420 Jul 7 '17 at 12:00

The easy bit is the superscript: that's just the charge. $++$ means a charge of $+2$.
The symbols for baryons are based on those chosen for the baryons formed of light quarks ($u$, $d$, $s$). They encode the isospin and quark content. The rules are relatively straightforward, but I'll refer you to the naming scheme for the full list.
A light-quark $\Xi$ has a quark content of $uss$ or $dss$. A heavy-quark $\Xi$ retains the single $u$ or $d$ and replaces one or both of the $s$ quarks with a $c$ and/or a $b$. This is denoted in the subscript: e.g. a $\Xi_c$ has $dsc$ or $usc$.