requirement even though it is often a useful way to proceed once it is known how many segments are to be acquired as will be specified by the user or at least determined from other things that the user does specify an order for those segments can be decided upon that order might be as in fig1 and 2 a strictly adjacent and consecutive one on the other hand it might be a random one suppose that instead of ten segments there were one hundred furthermore it may take some time for all one hundred triggers to occur if we let the oscilloscope display the frame buffer content as it is accumulated during the time required for the one hundred triggers the trace will be observed to u201c emerge u201d as it is acquired if the order of the segments is strictly left to right then the trace would start at the left and grow to the right if on the other hand the order is random or seemingly so then the trace will appear to u201c fill in all over u201d as time passes it could well be the case that some characteristic of the trace that is of interest.