Further to our conversations on the special properties of walls. Just to clarify my understanding of what it is that makes them different to other lines; 1. by default have -outline out set, and so define the boundaries of a scrap 2. by default have -clip on set, and so some symbols are clipped at the wall 3. have their own special subtypes, and altitude labelling, that are not available to other lines 4. are used by the scrap join algorithm to decide which lines to join I'd like to check that last one, which is as described in the Therion Book pg 30. However, is it really the wall line-type that the join scrap1 scrap2 7 statement uses to decide how to join the 7 passages that connect scrap 1 with scrap 2. Or is it the -outline in/out property of the lines that the join statement reacts to? (as could almost implied from outline definition pg 28 of Therion Book) This has implications if one joins scraps rather a lot. Bruce