The problem is, I have no idea what I can say to prove that I meet this criterion. I've never done any jobs which really demonstrate it, and invoking my social life seems tantamount to saying "some of my best friends are black Jewish lesbians, you know". I'm not even sure whether by "understanding of Equal Opportunities" they mean a general understanding of what it means, or an understanding of Equal Opportunities laws as they apply to employers and organisations, or ... or what.
The best I can think of for something to say is just making a statement along the lines of "I am firmly committed to Equal Opportunities in all situations, and believe that it is fundamentally unacceptable to discriminate against individuals on the grounds of ethnicity, religion, gender, sexuality, or any other irrelevant criteria".
Does that sound sane? Is there any point in saying it? It feels like such a basic thing to have to say that I can't really believe it serves any purpose; also, it doesn't prove anything -- anybody could write that and not necessarily mean it. I feel like there's a magic word that I need to say to convince them, and I just don't know it.