For notation, the assumption is that the two heavy quarks are both strange, denoted by a simple Ξ ; a subscript "c" is added for each constituent charm quark, and a "b" for each bottom quark. Hence Ξ c, Ξ b, Ξ cc, Ξ cb, etc. Unless specified, the non-up/down quark content of Xi baryons is strange (i.e. there is one up or down quark and two strange quarks). However a Ξ b contains one up, one strange, and one bottom quark, while a Ξ bb contains one up and two bottom quarks.