For me ULF is anything that has a diagonal dimension longer than 8X10. By that standard 5X12 and 7X11 qualify, though just barely.

If I were forced to adopt a less liberal standard, ULF would be 11X14, and anything with a longer diagonal than 11X14. That would include the common (and uncommon) formats of 10X12, 7X17, 8X20, 12X20, 14X17, 12X16, 18X22, and 20X24.

Sandy King