form functions (tag)

checked()

Outputs the html checked attribute.
disabled()

Compares two given values, and if they are the same, displays disabled = 'disabled' – an attribute for a form input field.
form_option()

Displays the sanitized option value. Used when displaying the wp option value for the value attribute of the <input> tag.
readonly()

Outputs the html readonly attribute.
selected()

Outputs the html selected attribute.
wp_readonly()

Outputs the HTML readonly attribute.
wp_referer_field()

Display or retrieve a hidden input field for form with the current page URI value (referer).