Bug#1136160: debian-policy: Clarify that Multi-Arch is not applicable for udebs

Nilesh Patra [10/May  1:04pm +0530] wrote:
> diff --git a/policy/ch-controlfields.rst b/policy/ch-controlfields.rst
> index 69467c4..f4d5fe9 100644
> --- a/policy/ch-controlfields.rst
> +++ b/policy/ch-controlfields.rst
> @@ -1381,8 +1381,10 @@ A Debian installation can combine packages from multiple architectures.
>  The ``Multi-Arch`` field enables individual packages to declare their
>  support for this feature, and influences the way dependencies are
>  handled.  It can be declared in binary package sections of a source
> -package template control file and in binary package control files.  The
> -permitted field values are ``no`` (default), ``foreign``, ``same`` and
> +package template control file and in binary package control files.
> +``Multi-Arch`` must not be used for udebs, as these semantics are out
> +of scope for the Debian installer.
> +The permitted field values are ``no`` (default), ``foreign``, ``same`` and
>  ``allowed``. Their semantics are described in the following sections.
>
>  .. _s-f-Multi-Arch-no:

Thanks.  Helmut, do you agree with using a "must not" here?