from file: form1.fdf
fields:
  - fdf:
      type: Tx
      name: topform.text1_0
  - fdf:
      type: Btn
      name: topform.button1.button1_0
      options: ['1', 'Off']
  - fdf:
      type: Btn
      name: topform.button1.button1_1
      options: ['2', 'Off']
  - fdf:
      type: Tx
      name: topform.text1_1
  - fdf:
      type: Tx
      name: topform.text2_0
  - fdf:
      type: Btn
      name: topform.button2.button2_0
      options: ['1', 'Off']
  - fdf:
      type: Btn
      name: topform.button2.button2_1
      options: ['2', 'Off']
  - fdf:
      type: Btn
      name: topform.submit