A comparison routine for comparing two data strings includes pre-processing, copying letters and digits into local buffers, comparing the contents of the local buffers using a left-to-right, walk-forward scanning algorithm, including selecting a first item from each buffer and comparing them and, if the two first items are the same, advancing to the next two items from each buffer, continuing with the comparison of subsequent buffer items until all pairs of items have been compared as long as no mismatch of items is found, and when a mismatch is encountered, the algorithm looks ahead in the data strings, searching for an identifiable pattern. A pair of independent search pointers are initially set to a first character in each data buffer and adjusted if a matching character pattern is found. A processing loop sequentially tests for a number of character patterns. If a matching character pattern is found, the match is scored, incrementing the score by one point for each matching character pattern that is found. If none of the character patterns is found, or the end of either string is reached, the processing loop is exited and the scoring data is collected.