@Override
	public void decode(Decoder decoder, SleighLanguage sleigh) throws DecoderException {
//		int element = decoder.openElement(ELEM_START_SYM);
		patexp = new StartInstructionValue();
		decoder.closeElement(ELEM_START_SYM.id());
	}
TripleSymbol with semantic value equal to offset of instruction's
current address
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/processors/sleigh/symbol/StartSymbol.java