If you use xrefs in your daily drafting work, you've probably seen the following situation at least once:
- Start a new drawing.
- Attach a DWG file as an external reference.
- Make lots of changes to the xref's layers, setting color and linetype to emphasize the areas you need.
- Do some work on top of the xref.
- Re-open the drawing later.
- Realize that all the layers you changed in the xref have reverted to their original state.
- Put all the layers back.
Familiar, yes? I know it's happened to me more times than I can count. Fortunately, there's an easy way to keep all your changes without having to redo them every time or use some other workaround.
Like so many other settings, this one's in the Options dialog. On the Open and Save tab, there's an area for External References. Look for the checkbox labeled "Retain changes to xref layers." When this is checked, any layer property changes you make will be remembered for future sessions. If you want the layers to always keep their original properties, uncheck the box.
The DWG icon next to the checkbox indicates that this option is saved per drawing, not per computer. In recent versions at least, the box is checked by default, but you can always set it to your preferred option in your template file. Then you'll always know what to expect.
(And for all you command line fans, this variable is known as VISRETAIN. Set it to 1 to remember layer settings, and to 0 to forget them.)