public override object WriteHeader(ByteBuilder bb)
{
bb.AddByte(Noun);
bb.AddByte(Verb);
bb.AddByte(Cond);
bb.AddByte(Seq);
bb.AddByte(Talker);
var offsetPos = bb.Position;
bb.AddShortBE(0); // Text offset
bb.AddThreeBytesBE(Unknown);
return(offsetPos);
}