Sub-LVDS is a differential low-voltage standard that is a subset of LVDS, and uses a reduced-voltage swing and lower common-mode voltage compared to LVDS. For sub-LVDS, the maximum differential swing is 200 mV compared to 350 mV for LVDS. The nominal common-mode voltage for sub-LVDS is 
0.9 V, while it is 1.25 V for LVDS. GPIO supports sub-LVDS in both receive and transmit modes. HSIO supports sub-LVDS only in the receive mode and requires an external resistor. The common mode voltage and differential voltage swing are key differences between Sub-LVDS and LVDS. PolarFire/PolarFire SoC to PolarFire/PolarFire SoC interfaces allow LVDS to Sub_LVDS and Sub_LVDS to LVDS since the data sheet specifications permit these levels to operate within their specified ranges.