With the 1998 Autofact trade show about to kick off (it opens September 29 in Detroit), it's worth thinking about what's important and what isn't in a CAD package, and how you should approach the important decision of which package to buy.

If you go to Autofact, you'll see aisle after aisle of exhibitors, each with staffs that will be delighted to give you demonstrations of the features their products have. You should visit as many of the exhibitors as possible in the time you'll be there. Check out the products' ease of use and their interoperability with other engineering software. Those are two of the most important features in any software package. And, as we have said before, ask the exhibitors if you can try the software yourself, either there on the show floor, or later in your own facility. You'll get a much better feel for the product if you try it out with your own hands on one of your own typical design problems.

Regarding other attributes beyond ease of use and interoperability, we've asked vendors of mid-range CAD (those products costing between $3,000 and $5,000) to help you by describing their products' most important features in a special section of this issue. Additionally, Bruce Boes of D.H. Brown and Bruce Jenkins of Daratech give you their advice on how to select a CAD system. Hiroshi Hara, chairman of the board of Microcadam, gave us these further thoughts in a recent interview:

- Solid modeling changes the design process, and generally requires more training than 2D CAD. But, depending on your objectives, it can make you more productive.

- Decide on your objectives before comparing features in different CAD systems. You may or may not need all the features a particular system offers, as interesting as they may seem. "When the pocket calculator came out and the price came down, many people paid extra to get additional functions," he says. "Later, they realized that all they did with the calculator was simple addition and subtraction."

- Check reference accounts.

CAD and other engineering software can be the most important tools you'll have for experimenting with different solutions to design problems and cutting design time and costs. Choose carefully.