numerical acronym

[Alice Faber]

--On Friday, November 5, 2004 4:48 PM -0600 "Mullins, Bill"
<Bill.Mullins at US.ARMY.MIL> wrote:

>  Is there a special word for an acronym or other construct that is partly
> formed by a numerical digit(s)?
>
> K-9
> P2P (peer-to-peer)
> many vanity license plates
> "b4" for "before"

I don't know if this is "official" terminology, but aren't these a kind of
rebus spelling?