Utilising the binary I/O package within AutoCAD to implement portable databases involved modifications in several areas. The changes are large, numerous, widespread, and significant, despite their limited impact on what gets written into the file. Installing them and debugging database compatibility was not a difficult design task; it was simply a matter of hacking, slashing, slogging, and bashing until every place where a nonportable assumption was made was found, and then fixing them all. ``That's what you were always best at,'' Galt interjected. I said that I hoped so, for I know of no single project I've done within AutoCAD which is so likely to destabilise the product as this one. The following paragraphs cover the highlights of each section.