What does this step in this protocol for the Yao's Millionaire Problem mean? I was reading “An Efficient Protocol for Yao’s Millionaires’ Problem” (Ioannidis and Grama 2003). In the proposed protocol in section three, it is written:


  (Step 4) For every $i$, $1 \le i \le d$, Bob obliviously transfers $A^\prime_{il}$ where $l = b_i + 1$.


(Some context: $d$ is a security parameter, $A^{\prime}$ is a matrix of size $d \times 2$, and $b_i$ are the bits of Bob's number.)

I understand the definition of 1-2 oblivious transfer, however, I am confused exactly what Bob is obliviously transferring.  Is it referring to the bits of $A^\prime_{il}$? If so, the paper explicitly says that only 1-2 transfers are used, so does that mean that $A^\prime_{il}$ is no larger than $2$ bits?
In here, it is 1-2 oblivious transfer meaning that for each $i$, the receiver gets $A'_{i1}$ or $A'_{i2}$ but the sender does not know which. The length of the elements $A'_{ij}$ is not important as long as you choose a correct oblivious transfer protocol.