I've been using Autocad and Autocad LT for years and I've never seen this. The objects (basically some lines) on the defpoints layer of a particular drawing have abruptly become completely inaccessible. The layer is not frozen. The objects are visible, but they can't be worked with. I first noticed that object snaps were not working on these lines. I then found out that the objects cannot be picked in any way, as for moving, copying, or deleting and cannot be listed using a cut pick. New lines drawn on the layer become inaccessible as soon as drawn. Only Undo can delete them. The whole layer has become unavailable for typical operations. I recovered the file. No change. I closed out of everything and rebooted and restarted. No change. I'm using !SlingShotMax form DRC Auto, so I tried opening the drawing with plain Autocad LT 2008. Same behavior. Similar drawings in the same package are not behaving in this way, so I think it's drawing specific. I've never encountered this before. What did I do wrong?
Its nothing to do with layer zero is it ? Possibly switched off or frozen ? I had trouble once before and it seemed that layer zero and defpoints worked together in some way but cant remember the details im afraid as it was a long time ago.
That was it! For some reason (user error) layer 0 was thawed but off! When I turned it back on access to objects on defpoints was restored. Thanks. I'll ponder the meaning of this. Maybe it's a feature.
But is there any harm or disadvantage in using the defpoints layer for detail locating frames or other such non-printing uses? (Other, of course, than the possibility of this little mixup with layer 0 repeating.)
I exchange files with LT2000 users regularly, although I cant remember if the non-plot option was in that release.
The problem comes on the occasions when you are dealing with a small building company etc. who don't actually use the program that much, or the people using it aren't that familiar with some of the features so you have to try to make it fool proof to try to force the drawings to be plotted properly.