Here are the data structures with brief descriptions:
[detail level 1234]
\NdepageDepage cms
 \NhtmlformHtmlform class and autoloader
  oNabstractsAbstract element classes
  |oCcontainerContainer element base class
  |oCelementBehold: the ├╝ber-class
  |oChtmldomDOMDocument for html-content
  |\CinputInput element base class
  oNelementsClasses for HTML input-elements
  |oCaddressDefault address fieldset
  |oCbooleanHTML single checkbox input type
  |oCcolorHTML color input type
  |oCcountryHTML-multiple-choice country input select
  |oCcreditcardDefault creditcard fieldset
  |oCdateHTML date input type
  |oCdatetimeHTML datetime input type
  |oCdatetimelocalHTML datetime-local input type
  |oCemailHTML email input type
  |oCfieldsetHolds HTML-fieldset specific attributes and methods
  |oCfileHTML file input type
  |oChiddenHTML hidden input type
  |oChtmlCan be used to insert custom HTML between rendered HTML elements
  |oCmonthHTML month input type
  |oCmultipleHTML-multiple-choice input type i.e. checkbox and select
  |oCnumberHTML number input type
  |oCpasswordHTML password input type
  |oCplaceholderAdds a placeholder for a form element
  |oCplaceholdermultiplePlaceholder for form multiple form values
  |oCrangeHTML range input type
  |oCrichtextHTML richtext element
  |oCsearchHTML search input type
  |oCsingleHTML-single-choice input type i.e. radio and select
  |oCstateHTML-multiple-choice States input select
  |oCstepSteps break up forms into separate consecutive parts
  |oCstepnavCan be used to insert a step navigation
  |oCtelHTML tel input type
  |oCtextHTML text input type
  |oCtextareaHTML textarea element
  |oCtimeHTML time input type
  |oCurlHTML url input-type
  |\CweekHTML week input type
  oNexceptionsHtmlform exceptions
  |oCduplicateElementNameExceptionThrown when there are duplicate element names
  |oCelementExceptionParent for element specific exceptions
  |oCelementParametersNoArrayExceptionThrown when element parameters aren't of type array on construction
  |oCinvalidElementNameExceptionThrown when element name is empty or contains invalid characters
  |oCunknownElementTypeExceptionThrown when attemting to instantiate an inexistent element class
  |\CvalidatorNotCallableParent for element specific exceptions
  oNvalidatorsValidators for HTML input-elements
  |oCclosureCustomizable validator for input elements
  |oCemailDefault validator for email input elements
  |oCnumberDefault validator for number input elements
  |oCrangeDefault validator for range input elements
  |oCregExCustomizable validator for input elements
  |oCtelDefault validator for tel input elements
  |oCurlDefault validator for url input elements
  |\CvalidatorParent validator class
  \ChtmlformMain interface to users