[TYPO3-commerce] How to add a checkbox to the billing-address-form?

[Sven Kalbhenn]

Hi folks,

I want to add a checkbox in the billing-address-form, for subscribing to a newsletter.
I found out, how to add a text-field:

plugin.tx_commerce_pi3._LOCAL_LANG.default.general_module_sys_dmail_newsletter = Newsletter abonnieren
plugin.tx_commerce_pi3.billing.sourceFields.module_sys_dmail_newsletter.mandatory = 0
plugin.tx_commerce_pi4.formFields.module_sys_dmail_newsletter.mandatory = 0

But I need a checkbox! So, how can I configure the type of the field???

I would appreciate any advice!

CU...Sven Kalbhenn