The date input plugin is a text input plugin that only allows dates to be posted. The value returned from pnForm::pnFormGetValues() is although a string of the format 'YYYY-MM-DD' since this is the standard internal Zikula format for dates.
You can also use all of the features from the pnFormTextInput plugin since the date input inherits from it.
This parameter enables the input to be pre-filled with the current date or similar other well defined default values. You can set the default value to be one of the following: