How to distinguish .udeb files from regular .deb files?

[Philipp Hahn <pmhahn@pmhahn.de>]

Hello,

I accidentally called "dpkg-name" on some *.udeb files and they got
renamed to .deb.

Looking inside dpkg-name, it tries to evaluate "Package-Type" [1], but
that is not contained in the control file of the binary package, so
always evaluates to "deb":
> 123     my $type = $fields->{'Package-Type'} || 'deb';                                                              

Is there some other (preferred) way to identify .udeb packages?

1. "Section: debian-installer"?

2. Some pages use the suffix "-udeb" or "-di" in their package names.

3. If the control file contains a "isinstallable" script.
> dpkg -I 'potential.udeb' | grep -q isinstallable

4. If the control files has a "Installer-Menu-Item" field:
> grep -I 'potential.udeb' | grep -q Installer-Menu-Item

Other ideas?
Or is there a definitive answer hidden somewhere?

Thanks in advance.

Philipp

[1]
<https://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Package-Type>