Don Bentz sends us guidelines he uses when working with referenced files in AutoCAD 2008 and Civil 3D 2008.
"No real tricks here, just a few basic things I do to manage xrefs. I prefer to prefix all the files I use as xrefs with an X (for example, X-BASEPLAN.DWG) and keep them all in one folder, with subfolders if needed. It also helps to use meaningful names. With the X prefix, the xrefs will all be together in the Layer Manager, making navigation easier. When xrefs get revised, I save the old one to a superseded folder with the date and or revision appended to the file name. The file in the Xref folder then gets overridden with the revised version (The name stays the same). I always make sure xrefs have been fully purged (both purge and -purge (for Regapps), audited, and all unused annotative scales have been removed. The last item is very important.
"Make sure all xrefs use 0,0,0 as the insert point (WCS) and the units are set correctly. Also be sure Insunits is set correctly. (Some people prefer to set everything to unitless).
"I always attach xrefs as an overlay. That way there are never any circular references. I've come across drawings where several xrefs have been attached to one drawing and then that drawing is xref'd into others. This can be very confusing. Users should make themselves familiar with the differences between Attachment and Overlay.
"I add text to my drawings in the individual drawing sheets rather than in the xrefs. For those who miss the Xref Manager from previous releases, it is still available via ClassicXref and ClassicImage. There have been times when the Xref Manager has been extremely slow, usually due to an image attachment, and using ClassicXref brings up the Xref Manager instantly."
Notes from Cadalyst Tip Patrol: Proper use of referenced files is fundamental to AutoCAD and drawing management. One other item to consider is to reference your files through a full path or a relative path. A full path reference means that AutoCAD will look in a specific folder, down to the drive letter. A relative path reference will look inside the working folder. This is handy when archiving drawing files or even when sending files with xrefs to outside users. If your project folder is on the “P” drive, your client needs to have a P drive or your full path references won’t work.