For messages that use the RR Short Protocol Discriminator format, use the following PDU:

RR-Short-PD-PDU ::= SEQUENCE {
    rr-short-PD INTEGER (0..1) DEFAULT 0,
    msgType RR-SHORT-CLASS.&msgType ({RR-Short-PD-Messages}),
    short-layer-2-header INTEGER (0..3) DEFAULT 0,   
    data RR-SHORT-CLASS.&Value ({RR-Short-PD-Messages}{@msgType})
}                
            

The msgType field determines the type of the value in the data field.