Meaningful only if the MaxLen entry is present in the text field dictionary and if the Multiline, Password, and FileSelect flags are clear. If set, the field is automatically divided into as many equally spaced positions, or combs, as the value of MaxLen, and the text is laid out into those combs.

If set, the field is a combo box; if clear, the field is a list box.

If set, the new value is committed as soon as a selection is made with the pointing device. This option enables applications to perform an action once a selection is made, without requiring the user to exit the field. If clear, the new value is not committed until the user exits the field.

If set, the field does not scroll (horizontally for single-line fields, vertically for multiple-line fields) to accommodate more text than fits within its annotation rectangle. Once the field is full, no further text is accepted.

If set, text entered in the field is not spell-checked.

If set, the combo box includes an editable text box as well as a drop-down list; if clear, it includes only a drop-down list. This flag is meaningful only if the Combo flag is set.

If set, the text entered in the field represents the pathname of a file whose contents are to be submitted as the value of the field.

If set, more than one of the field’s option items may be selected simultaneously; if clear, no more than one item at a time may be selected.

If set, the field can contain multiple lines of text; if clear, the field’s text is restricted to a single line.

If set, the field must not be exported by a submit-form action.

(Radio buttons only) If set, exactly one radio button must be selected at all times; clicking the currently selected button has no effect. If clear, clicking the selected button deselects it, leaving no button selected.

No flags.

If set, the field is intended for entering a secure password that should not be echoed visibly to the screen. Characters typed from the keyboard should instead be echoed in some unreadable form, such as asterisks or bullet characters.

If set, the field is a pushbutton that does not retain a permanent value.

If set, the field is a set of radio buttons; if clear, the field is a check box. This flag is meaningful only if the Pushbutton flag is clear.

(PDF 1.5) If set, a group of radio buttons within a radio button field that use the same value for the on state will turn on and off in unison; that is if one is checked, they are all checked. If clear, the buttons are mutually exclusive (the same behavior as HTML radio buttons).

If set, the user may not change the value of the field. Any associated widget annotations will not interact with the user; that is, they will not respond to mouse clicks or change their appearance in response to mouse motions. This flag is useful for fields whose values are computed or imported from a database.

If set, the field must have a value at the time it is exported by a submit-form action.

If set, the value of this field should be represented as a rich text string.

If set, the field’s option items should be sorted alphabetically. This flag is intended for use by form authoring tools, not by PDF viewer applications. Viewers should simply display the options in the order in which they occur in the Opt array.