The CTRL channel exists only when Rounding has been selected and exists to convey only the rounding bit (referred to in this document as ROUND_CY). This bit occupies bit 0 of TDATA for this channel. However, due to the byte-oriented nature of TDATA, this means that TDATA has a width of 8 bits. ROUND_CY is added to the rounding constant of 0.01111..., making the rounding constant either 0.01111.. or 0.100... Therefore, setting this bit to 0 causes the rounding to be rounded to negative infinity; setting it to 1 causes it to be rounded to positive infinity and setting a new random value for each sample gives unbiased random rounding. See Rounding for more information.