From opening paragraphs:
This book deals with technology and how it interacts with magic and psionics. The technology herein uses the real world as a rough guideline regarding what technology can and cannot do, with some leeway granted by the idea that in a world of magic, the rules of nature can be bent and sometimes broken. Some of the devices may seem unrealistic, but abilities such as cloaking and temporal manipulation make technology roughly on par with magic. However, some things, such as the wish spell, are not replicated by technology, and are just too fantastic. This book was written to be a viable alternative to magic, but not to replace it.
There are no assumptions made about the settings this technology is used in. The information is presented to make it feel technological (by using charges and physical devices) and still retain balance within the d20 system. While the relationship between technology and magic (and psionics) is discussed, neither magic nor psionics is required to use these devices. These rules could just as easily represent real-world technology at the end of the 19th century (with the exception of those items that bend the rules, such as cloaking and temporal manipulation devices), as it could describe technology that springs up in a typical fantasy setting.