More & more distros are releasing "EFI" or "UEFI" required bootable versions, meaning a non-UEFI system won't do much of anything. Often, non-UEFI systems won't even show any issue, or error, they simply will sit there and do nothing. We have started to indicate this in the distro description so if you see a "UEFI"l designation in the description, be sure you have a newer/UEFI based systems. For those having no idea what UEFI means, here is a quick overview:

UEFI stands for Unified Extensible Firmware Interface. It is a replacement of the old PC BIOS (Basic Input/Output System), which had various limitations and the industry all agreed it made sense to enhance and drop the old (orginal IBM PC) approach. As a quick explanation of how the BIOS or UEFI fits into the puzzle, imagine the CPU (Central Processing Unit) and basic computer hardware - CPU, memory, hard drive, monitor. So when you turn on this hardware, what does it do? Where does it start reading instructions for the CPU? The BIOS was a starting point to initialize the hardware, input and output devices, and enough instructions to start loading an operating system (i.e. load a boot program from the hard drive (or floppy, or CD/DVD, or USB, or Network)). Originally the BIOS was a ROM (or Ready Only Memory), and slowly evolved into flash memory (that can be rewritten/updated, but typically required a special process to do this). So BIOS evolved into a firmware interface, and various players in the industry wanted to do things like customize systems, so the "extensible" aspect was added, and other players wanted the Secure Boot concept, where only things authorized by the hardware manufacturer could actually boot and control the hardware (but note this is also extensible for a more general approach), or could be bypassed with a Compatibility Support Module (CSM) that supported the "old" way to boot (i.e. the BIOS way). In order to make this work for all the players in the industry, a consortium got together to define this Extensible Firmware Interface, so we all now have the "Unified" Extensible Firmware Interface being the way personal computers are designed and built. A few other notes: UEFI is processor agnostic and supports x86, x64, ARM, etc. Instead of low-level assembler, UEFI has implementations in C language. There is a UEFI form that promotes the UEFI specification. Intel originally owned an EFI implementation, so the UEFI is more collaborative. ACPI was handled to the UEFI forum - this is the Advanced Configuration and Power Interface which manages things like system, device, processor power management, configuration plug and play, battery, system events, etc.

We have also added a few "By Request" items with "Untested" - this is because the distro provider has specific machine or graphic card requirements, and we do not have a machine that meets these specific requirements, so are unable to boot and test the release. We are able review the partitions and data on the media, but we have always tested and verified downloads to make sure that what deliver is bootable and imaged correctly. So this is not something we would do except with a By Request distro and acceptance of the risk by the requestor, and this is indicated with "Untested" added to the description.