Part 10 of Ralph Griswold's series on designing with L-Systems, showing how to interpret L-System strings as profile (block) threading and treadling sequences. It gives two worked examples with seeds, rewriting rules and the first four generations, one with a three-times growth in length and one with palindromic rules, and shows profile drafts generated from generation 4. It also discusses limiting the number of blocks, using block repetition to vary pattern widths, and ideas such as separate L-Systems for threading and treadling or width-sequence interpretation.