I never use 3d, never knowingly specify a Z value, accepting that all will be created at 0.0 elevation. However I just discovered a problem that I believe is sourced to this non zero elevation with some closed polylines as I hatch (command "_.hatch" ...) them under program control (they hatch normally when done manually). Take this one drawing example. It has three entities, all closed LWpolys. The largest one is a simple rectangle that surrounds a smaller hollow letter M, and that, in turn, surrounds a smaller poly shaped like the letter D. Under program control the hatch command competely ignores the letter M as the island and ceases the hatching at the innermost D shape. Before I suspected different elevation of these three entities I used the Boundary command workaround. After that command created three new entities I erased the older three and was surprised that hatching proceeded normally. Today I was determined to learn why so I checked entity properties, comparing the new polys with the old ones. There is where I found two of the old ones at non zero elevation. The Boundary command apparently does its creation at 0.0 elevation. Unless I get a suggestion otherwise, I will probably embed a code snippet to sniff the elevation of each entity prior to hatching, change those that are non zero, and proceed. My question, however, is why? What could I possibly be doing that inadvertently places closed polylines onto a non zero elevation? It's not much, some 0.0006917 in this case. Len Miller
