Bootable USB Key - Partition Table Format?

Can anyone confirm for me that I am not obliged to use msdos for partition table on a USB key in order to have it recognized as bootable by an “ancient” BIOS?

BIOS Information
	Vendor: American Megatrends Inc.
	Version: 2603   
	Release Date: 04/13/2011

Can it be done using a GPT-formated disk?

IF so, how?

I do mean hownot requesting any suggestions for tools that will do it all for me.

I would like to know if this is possible before burning two different ISOs, fresh images for each of xubuntu and ubuntu-server 26.04 LTS.


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