The fieldset element represents a set of form controls grouped under a common name.
an optional legend element, followed by flow content
global attributes & name & disabled & form
A fieldset element must have both a start tag and an end tag.
any element that can contain flow elements
interface HTMLFieldSetElement : HTMLElement {
attribute boolean disabled;
readonly attribute HTMLFormElement form;
attribute DOMString name;
readonly attribute DOMString type;
readonly attribute HTMLFormControlsCollection elements;
readonly attribute boolean willValidate;
readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
void setCustomValidity(in DOMString error);
};