[Several][a] [guides][b] to creating disk images of macOS install media (using the `createinstallmedia` command) recommend creating the disk image like this:

[a]: https://osxdaily.com/2020/07/20/how-convert-macos-installer-iso/
[b]: https://www.tweaking4all.com/software-development/create-macos-install-media/

    hdiutil create \
        -size 10g \
        -type UDTO -layout SPUD -fs JHFS+ \
        ~/Desktop/installer.cdr

Here, `-layout SPUD` creates the disk image with an [Apple Partition Map][APM], rather than the default, more modern [GUID Partition Table][GPT].

[APM]: https://en.wikipedia.org/wiki/Apple_Partition_Map
[GPT]: https://en.wikipedia.org/wiki/GUID_Partition_Table

According to the `hdiutil` manpage,

> `SPUD` causes a DDM and an Apple Partition Scheme partition map with a
single entry to be written.  `GPTSPUD` creates a similar image but with a
GUID Partition Scheme map instead.  When attached, multiple `/dev` entries
will be created, with either slice 1 (GPT) or slice 2 (APM) as the data
partition.  (e.g. `/dev/disk1`, `/dev/disk1s1`, `/dev/disk1s2`).
>
> Unless overridden by `-fs`, the default layout is `GPTSPUD` (PPC systems
used `SPUD` prior to Mac OS X 10.6).  Other layouts include `MBRSPUD` and
`ISOCD`.  `create -help` lists all supported layouts.

Some [decades old blogs](https://www.informit.com/articles/article.aspx?p=517379&seqNum=3) mention that GPT disks are not compatible with PowerPC Macs, and very old versions of macOS (prior to 10.4.2) do not understand GPT partition maps at all. And years ago there was briefly an [incompatibility with VirtualBox](https://www.virtualbox.org/ticket/14490) when using GPT-formatted install media. So perhaps APM was considered a more broadly compatible format.

But these are just theories. Is there actually a specific reason to continue using APM-flavored partition maps for macOS install media?