I don't think this will render properly (but my mental rst compiler sucks) – but what I think will happen is that it will interpret the below as preformatted (since that's what `::` does) – have you double checked that that's not the case?

Also presumably here you mean "if you wanted to check whether a Draft 3 schema was valid" or "validate a schema you created against the Draft 3 meta-schema" if you wanted something like your wording.