In the preface of The Tester's Pocketbook Paul says:

"Although my own background is in software testing, I have tried throughout the Pocketbook to avoid the use of terms like software, programmer, program, module etc. because testing is about so much more than software. Instead of software, I have used the word system to label what we test. I’ve tried to make the text as generic as possible so that it supports the testing of any system. Does this mean the Pocketbook describes the approach to testing anything? Well, that would be neat but highly unlikely.

In my career, I've tested programs, software systems, interfaces, hardware, firmware, buildings, furniture, telephones, concrete and people. This Pocketbook attempts to describe the thought processes associated with testing systems in the broadest sense and is not specific to any one milieu, technology, organisation, culture. It is context-neutral.

By the way, I’ll discuss testing mainly in the context of projects, but testing isn’t restricted to systems development projects. Testing might also take place in a maintenance or business-as-usual environment to ensure repairs or other changes to production systems work correctly. Testing might also be used to explore how a system works for the purpose of an evaluation.

The Pocketbook won’t make you a demon tester. It won’t teach you anything about test process, test case design or methodology. What it will do is introduce (or remind you of) the pre-requisites, thinking processes and decision-making you need to do a half-decent job."