Developer Area/Core Subsystems/Form API (Pieforms)/Form API i18n

Form rules can be internationalised to different languages. A rule can set it's own language string on the element itself. But generally we allow the form rule to fetch the language string based on the pieform plugin, pluginname, key. For example for the required rule we have a language string $string['rule.required.required'] = 'This field is required.';