Global Standards for the Microelectronics Industry
serial data input/output [SDQ(n)(x)]
On a device having a serial data access port, the pins that serve as serial data output(s) when in the read mode and as serial data input(s) when in the write mode. When the device or the serial port is not selected or enabled, the output(s) are in a floating (Z) state. When the numbering of the serial data input/outputs is significant for device operation, the serial data input/outputs are numbered beginning with 0. For devices where data bit groupings have independent control, an additional suffix "x" is applied. "x" takes the values of a, b, c, etc.