 Even though neither Borel test spaces nor quantum test spaces are semi-classical, one might argue that in any real laboratory situation, semi-classicality is the rule. Ordinarily, when one writes down in one’s laboratory notebook that one has performed a given test and obtained a given outcome, one always has a record of which test was performed. Indeed, given any test space \(\mathcal{A}\), we may always form a semi-classical test space simply by forming the co-product (disjoint union) of the tests in \(\mathcal{A}\). More formally: