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A programming product is the next level up from a program. This product must have documentation. It also needs to be developed so any developer can step in and maintain it. These extra constraints mean it will take three times longer to develop than writing a little program.
Next up is the programming system. It contains multiple programs which communicate with each other. Developing such a beast takes three times longer than a programming product.
Finally we have the programming system product. This one cost even more in terms of development effort. You can quickly get to a level of complexity where the development might be problematic.
Next time I cover some issues that come up when you try to work on a programming system product.