Where structures defined by this standard are incorporated into mixed-signal circuits, the testability problems posed by such circuits are mitigated by way of improving the controllability and observability of mixed-signal designs and supporting mixed-signal built-in test structures in order to reduce both test development time and testing costs and to improve test quality. In particular, these standardized test features allow mixed-signal (analog and/or digital) electronic components, printed circuit assemblies, and electronic systems to be accessible to external or built-in test equipment for interconnect test, parametric test, and internal test. A further purpose of this standard is to define the descriptive elements of BSDL and specified extensions sufficient to support the development of automated test algorithms used for testing interconnections between devices that adhere to this standard and, where practical, between such devices intermixed with devices that incorporate IEEE Std 1149.1 or IEEE Std 1149.6 as well. The descriptive elements defined by this standard also largely support the automated construction of analog tests for external components attached to or between components that implement this standard with the caveat that such tests may subsequently require modification to account for undocumented analog features within the conformant components.