code: public void addReadFields(int input, FieldSet readFields) {
  
  		if (input != 0 && input != 1) {
  			throw new IndexOutOfBoundsException();
  		} else if (input == 0) {
  			this.readFields1 = (this.readFields1 == null) ? readFields.clone() : this.readFields1.addFields(readFields);
  		} else {
  			this.readFields2 = (this.readFields2 == null) ? readFields.clone() : this.readFields2.addFields(readFields);
  		}
  	}
docs: Adds, to the existing information, field(s) that are read in
  the source record(s) from the first input.
  
  @param input the input of the read fields
  @param readFields the position(s) in the source record(s)