void initPtga()
	{
		if( expression == null )
		{
			init();
		}
		if( (expression == null) || (expression.size() == 0) )
		{
			return;
		}
		Ptg p;
		//if the usual case of 1 reference-type (area, ref, memfunc...) ptg:
		if( expression.size() == 1 )
		{
			p = (Ptg) expression.get( 0 );
			if( p.getIsReference() )
			{
				ptga = p;
			}
		}
		else
		{ // otherwise it's a formula expression
			p = FormulaCalculator.calculateFormulaPtg( expression );
			if( p.getIsReference() )
			{
				ptga = p;
			}
		}
/*		
		if (expression != null && expression.size() > 0){
			// this may be an invalid rec
			for(int t=0;t<expression.size();t++){
				Ptg p = (Ptg) expression.get(t);   
				p.setParentRec(this);
				if (p.getIsReference())	 
					ptga= p;
				// otherwise it's a constant named range expression
			}        
		}
*/
	}