Alternating Sitting and Standing. Claimant with ability to alternate between sitting and standing positions found to have sufficient residual functioning capacity for unskilled work. The need to alternate between sitting and standing does not preclude all sedentary work. SSR 83-12 provides that "unskilled jobs are particularly structured so that a person cannot ordinarily sit or stand at will." This does not mean that there are no sedentary unskilled jobs which allow a person to sit and stand at will.