Ethnic Diversity 101

A curious Blog reader brought to my attention that the web site of the local Republicans has a link for "contact information" for all of the fall candidates. On that link (a pdf file), you get to see the basic information for the candidates - the normal junk - with the exception of the very interesting category of "ethnicity." Why is that on there? (And the sheet even lets you know "AE" stands for "American European".)