The ADN Plugin of the Month for September is now available. It's a Digital Signature Stamp for AutoCAD. I know the government sales division will be excited to see this plugin. This plugin was written by Maanger of DevTech Americas, Stephen Preston based on a similar ObjectARX (C++) custom entity implementation written by Senior Developer Consultant, Fenton Webb. The plugin allows you to specify a BlockReference that will change its display when plotted to indicate whether the drawing had a valid digital signature at the time of plotting.
Take a look at the source code for this one and see how it works. You may even have ideas for extending it. Let us know your thoughts at firstname.lastname@example.org. Thanks.
Dancing to "Signed, Sealed, Delivered, I'm Yours" is alive in the lab.