well lots of things
dxb drawing exchange binary format
similar to a dxf but binary breaks everything down into its simplest form
say you need to give someone an electronic printable version of your drawing but you dont want to give him your entire drawing just what it would look like if it was printed you set up that dxb printer print to dxb start a new drawing insert the dxb and ther you have it also if say this person as a non autocad product that reads DXF after you insert it into the drawing you can save as a DXF
This can be quite helpful when going back and forth between muliple cad apps if everyone helps everybody the world will be a better place
