On their webpage at the top of the graphic it has "CU Fraternity & Sorority Index" then has "Historically Ethnic Groups", "Panhellenic" & the other groups listed below. Also, on the left of the graphic it has "Greek Life at Boulder" - so I would guess that the reason for not calling the groups "Historically Ethinc Fraternities & Sororities" is because it is very obvious all throughout the web page that it is the greek life page & it has "Fraternity & Sorority" listed on the page several times in other spots. It would be redundant to have Fraternities & Sororities listed after the group's name.