[ASN.1] constrained TYPE-IDENTIFIER

[Augustin.Chevalier]

Hello,

I don't really understand why using TYPE-IDENTIFIER.&Type(IFPPacket) instead
of IFPPacket itself in the syntax (extracted from T38) below! If I'm not
mistaken the result should be the same : only the values of the IFPPacket
type are expected here.
Have someone an explanantion.

IFPPacket::=SEQUENCE
{
        type-of-msg Type-of-msg,
        data-field Data-field OPTIONAL

}
UDPTLPacket::=SEQUENCE
{
        seq-number      INTEGER(0..65535),
        primary-ifp-packet TYPE-IDENTIFIER.&Type (IFPPacket),
        error-recovery CHOICE
        {
                secondary-ifp-packets SEQUENCE OF TYPE-IDENTIFIER.&Type(IFPPacket),
                fec-info SEQUENCE
                {
                        fec-npackets    INTEGER,
                        fec-data        SEQUENCE OF OCTET STRING
                }
        }
}


many thanks

Augustin Chevalier