Any drawing created in AutoCAD 2008 and later which uses Multileaders will present problems to users of AutoCAD 2007 and earlier. The users of the earlier release will find that rather than having leaders to deal with, they have proxy objects. As a result, it is impossible to edit these leaders in any way other than erasing them. Also, depending on the setting of the PROXYSHOW system variable in the earlier release, the objects may not display at all, or could display only as rectangles.

If the user of 2008 or later used the background mask feature when creating Multileaders, they might appear to be fine on the screen. But when plotting, the text part of each leader will come out as a filled black rectangle. That sort of thing has a long history of happening with wipeouts in some cases, depending on the output device and driver. This problem is different because it happens every time, and with all output devices.

What can be done if you are the recipient of such drawings? The -ExportToAutoCAD command, which can be used to create a version of the drawing with most proxy objects converted to standard AutoCAD objects, does not work with Multileaders. So I can see three options, in descending order of desirability:

1. Upgrade to a more recent release of AutoCAD. Depending on your circumstances, this may not be a practicable solution.
2. Forbid the use of Multileaders among your users and all parties producing drawings for you. This also may not be a practicable solution.
3. Explode the leaders. This results in them becoming dumb text and lines, with no background masking. However, the masking can be easily re-established using the Textmask command that is part of the Express Tools.

It fills me with horror to suggest something as awful as exploding anything even remotely dimension-like, but if you have one of these drawings and you’re forced by circumstances to use AutoCAD 2007 or earlier, what alternative do you have?

This, along with various other Multileader design issues (such as non-integration with dimension styles), appears to be a natural by-product of Autodesk’s decision to add these objects part-way through the lifetime of a DWG version. The 2007 DWG format is shared by AutoCAD 2007, 2008 and 2009, but this interoperability issue affects even users of those releases that supposedly share the same format. Users of vertical AutoCAD variants are, unfortunately, accustomed to this sort of thing happening every year.