Numerous types of form fields are built into Joomla! The following describes the common standard types and their parameters.
Form Field Type Subform
The form field type subform provides a method for using XML forms within another or for reusing forms within an existing form. When the
multiple attribute is set to
true, the contained form is repeatable.
The field has two
predefined layouts for displaying the subform as either a table or a div container, as well as support for custom layouts.
I show an example of an XML field definition for repeatable mode below. Fundamental is the line
<field name="domains" type="subform" label="COM_USERS_CONFIG_FIELD_DOMAINS_LABEL" hiddenLabel="true" multiple="true" layout="joomla.form.field.subform.repeatable-table" formsource="administrator/components/com_users/forms/config_domain.xml" />
I have not found an example for
multiple="false" in Joomla. A use case might be if the number of subforms depends on a condition. Then
multiple="false" can be useful.