Coorelation in Load Runner

Hi,

How to use a correlated value in another correlation within the same request.

I have a tag which has two dynamic values. After correlating the first dynamic value (Say A), how can I use A to correlate another value (Now A has become the left boundary for this dynamic value) within the same request. As the first value changes the second value changes acc to it.

eg: abc=012_(Dynamic value 1)_xyz_"(Dynamic value 2)"_rst;

Both the values are of different length for every request.

Thanks in advance!