The /Ff field flags of a button field (ISO 32000-1 Table 227), alongside the
three every field carries (Table 226).
Fields
:read_only— the field may not be changed by the user.:required— the field must have a value when the form is submitted.:no_export— the field is omitted from a submission.:no_toggle_to_off— one radio button in the group must always be selected; clicking the selected one does not clear it.:radio— the field is a group of radio buttons.:push_button— the field is a push button, which holds no value and acts only through its/AAactions.:radios_in_unison— radio buttons in the group that share an on-state name are selected and cleared together.:raw— the undecoded/Ffinteger, for bits this struct does not name.
:radio and :push_button are the two bits
PdfElixide.Form.Field.Button's :kind reports, with :push_button taking
precedence over :radio on a field that sets both. See the "Field kinds and
flags" section of the Forms guide.