You can clone with
HTTPS or Subversion.
Attribute aria-required not allowed on element input at this point.
…ox" id="ApplicationForm_Form_Terms" required="required" aria-required="true" />
A similar thing happens with DropdownField(). It needs a default empty string see: http://www.maxdesign.com.au/2012/11/03/select-required/
While the checkbox field is the opposite, it can't have a value="x" if it is required.