Xilinx CoolRunner-II complex programmable logic devices (CPLDs) support the EIA/JEDEC LVTTL 3.3V and LVCMOS 3.3V, 2.5V, 1.8V and 1.5V I/O standards. This paper addresses questions concerning the use of 2.8V (+/-5%) and 3.0V (+/- 5%) I/O levels with the Xilinx CoolRunner-II CPLDs. It also provides guidance for the operation of Xilinx CoolRunner-II CPLDs at non-standard voltages.