private static ContactRelation CheckContact(ERA[] rel)
    {
    	ContactRelation contact = ContactRelation.NULL;
    	ERA rel1 = rel[0];
    	ERA rel2 = rel[1];
    	if (rel1 != ERA.TAKES_PLACE_BEFORE && rel1 != ERA.INVERSE_TAKES_PLACE_BEFORE
    			&& rel2 != ERA.TAKES_PLACE_BEFORE && rel2 != ERA.INVERSE_TAKES_PLACE_BEFORE)
    	{
    		contact = ContactRelation.SURFACE_TO_SURFACE;
    	}
    	return contact;
    }