Roxy, what syl20 means is, no matter what value you use for n (2,3,4,etc) the Bed Level Correction Matrix displayed after G29 finishes is always in a 3x3 arrangement. Is there some averaging going on? If I do a G29 n5, the BLCM is still 3x3. I've done searches, but I haven't found any post anywhere that explains how the BLCM works, how it's used.