Le caselle combinate forniscono agli utenti un menu a discesa e da questo menu è possibile selezionare solo una singola risposta. Puoi aggiungere voci di menu per le caselle combinate tramite la categoria Opzioni nelle Proprietà del campo.

To add a combo box field:

1. Open the PDF in Nitro Pro.

2. On the Forms ribbon, in the Form Fields group, click Combo Box.

3. On the page, drag the pointer where you want the field to appear.

4. Double-click on the field and do one of the following (depending on your preferences):

• In the Properties context tab, name the field and set its appearance settings.
• In the Properties dialog, name the field and set its appearance settings.

5. Do either of the following:

• If you’re using the Properties context tab, in the More group, click Properties and then Options.
• If you’re using the Properties dialog, click the Options tab.

6. Select Options. Click in the Item field and enter a name in the text box. Click the Add button to add the text to the Items list. Type an export value in the Export Value text box. Continue adding items following the same steps.

7. Click the Sort Items check box if you want the list sorted in alphabetical order. Select items in the list and click the Down/Up buttons to rearrange the items in the list manually. Select an item and click Delete to remove it from the list.

8. If you want a user to type an item instead of choosing from the list, click the Allow custom text input check box.

9. Format. If you want a format other than text, such as a date or custom format, chose an option from the Select format category drop down menu.

10. Validation. If you want the field data to be validated, you need to know JavaScript. Check Run custom validation script and type the JavaScript code to validate the field data.

11. Calculate. If the field is to be calculated, check an option for calculating data.

To edit a combo box form field:

1. Open the PDF in Nitro Pro

2. On the Form ribbon, in the Form Fields group, do either of the following:

• Click the field type that corresponds to the field you want to edit.
• Click Select Fields.

3. Double-click the field to begin editing its attributes.