We should use this syntax as it is more intuitive and does not depend on a database-specific syntax (like ENUM(...)). Therefore it is easier to implement.

{{{
#!xml
<column name="enum_col" type="enum" />
	<element value="a" />
	<element value="b" />
	<element value="c" />
</column>
}}}

Enums can be "emulated" in PHP using a class:
{{{
#!php
<?php

$enum = new ColEnum(ColEnum::ELEMENT_A);

// generic Enum-class
abstract class Enum {
	private $value = null ;

	public function __construct($value) {
		$this->value = $value;
	}

	public function is($value) {
		return $this->value === $value;
	}
}

class ColEnum extends Enum {
	const ELEMENT_A = 0;
	const ELEMENT_B = 1;
	const ELEMENT_C = 2;
}
}}}