grammar
{
    start = element request
    {
        (QuickPoll | Poll)? & Control?
    }
    Poll = element poll
    {
        element status { empty }? &
        element duration { empty }? &
        element position { empty }? &
        element get {
            attribute property { text }
        }* &
        element info { empty }?
    }
    QuickPoll = element quickpoll
    {
        element status { empty } |
        element duration { empty } |
        element position { empty } |
        element get {
            attribute property { text }
        } |
        element info { empty }
    }
    Control = element control
    {
        element play {
            attribute file { text },
            attribute add { "true" | "false" }?,
            attribute sequence { "true" | "false" }?
        }? &
        element pause { empty }? &
        element stop { empty }? &
        element set {
            attribute property { text },
            attribute newvalue { text }
        }? &
        element position {
            attribute time { xsd:nonNegativeInteger },
            attribute absolute { "true" | "false" }
        }? &
        element fastforward {
            attribute amount { xsd:nonNegativeInteger }
        }? &
        element rewind {
            attribute amount { xsd:nonNegativeInteger }
        }?
    }
}