silverstripe-userforms/code/formfields/UserFormsStepField.php

<?php

/**
 * Represents a page step in a form, which may contain form fields or other groups
 */
class UserFormsStepField extends UserFormsCompositeField {

	private static $casting = array(
		'StepNumber' => 'Int'
	);

	/**
	 * Numeric index (1 based) of this step
	 *
	 * Null if unassigned
	 *
	 * @var int|null
	 */
	protected $number = null;

	public function FieldHolder($properties = array()) {
		return $this->Field($properties);
	}

	/**
	 * Get the step number
	 *
	 * @return int|null
	 */
	public function getStepNumber() {
		return $this->number;
	}

	/**
	 * Re-assign this step to another number
	 *
	 * @param type $number
	 * @return $this
	 */
	public function setStepNumber($number) {
		$this->number = $number;
		return $this;
	}
}