Add 'role' data attribute. Note, that 'role' attribute is a part of reach ARIA API described here: http://www.w3.org/TR/wai-aria/ Among 'role', it defines lots of aria-* attributes

fun main () : transaction page =
    let
        val x = 1
        val y = "Hello"
        val z = 3.45
    in
        return <xml>{[x]}, {[y]}, {[z]}</xml>
    end