[(1->4)-beta-D-xylan](n) + UDP-alpha-D-xylose <=> [(1->4)-beta-D-xylan](n+1) + UDP + H(+)
[(1->4)-beta-d-xylan](n) + udp-alpha-d-xylose <=> [(1->4)-beta-d-xylan](n+1) + udp + h(+)
[(1->4)-beta-D-xylan](n) + UDP-alpha-D-xylose <=> [(1->4)-beta-D-xylan](n+1) + UDP + H(+)
[(1->4)-beta-d-xylan](n) + udp-alpha-d-xylose <=> [(1->4)-beta-d-xylan](n+1) + udp + h(+)