Can Enums be integral types?

[Manfred Nowak via Digitalmars-d-learn]

In the specs(17) about enums the word "integral" has no match. 
But because the default basetype is `int`, which is an integral 
type, enums might be integral types whenever their basetype is an 
integral type.

On the other hand the specs(7.6.5.3) about types say
| A bool value can be implicitly converted to any integral type,
| with false becoming 0 and true becoming 1.
This seems senseless, when the enum has no names defined for one 
of these values.