Apologies for asking a question previously answered. Someone asked this about a year ago, and Stacho or Martin provided an answer, unfortunately I can not find it in the forum archives. The partial log file transcript below suggests to me that there is a minor problem with my wall drawing in or after [181] and a fatal problem with something in or after [186]. How do I locate the objects referred to by the numbers in square brackets? (This particular one is odd, 'cos it worked fine yesterday, and all my th-config files that compile individual components of this master file still compile perfectly - must be an inadvertent change I made somewhere.) Thanks Bruce [173] [174] [175] [176] [177] [178] [179] [180] [181] [Warning: scrap outline intersects itself in scrap Late08ROPlan_s2@Late08.Bulme r] [182] [183] [184] [185] [186] ! angle(0,0) is taken as zero. l_arrow_SKBB->....rotated(angle(thdir((EXPR0),0))+ 90)shifted(point0of(EXPR0)... l_mapconnection->....PenB);l_arrow_SKBB((EXPR0),3) ;thdrawoptions(); l.18855 ...ion(((229.38,96.96) -- (229.38,96.96))) ; The `angle' between two identical points is undefined. I'm zeroing this one. Proceed, with fingers crossed. ! angle(0,0) is taken as zero.