What Would Interactive Testing With 1687 Look Like?

As PDL has been developed to be syntactically compatible with TCL, it is possible to use an interpreter to enhance test routines with programming features, such as variables, flow control, etc.. Moreover, one of the big novelties of IEEE 1687 is the native support of interactive behaviour thanks to the PDL-1 instruction set. which allows data read from the target system to be returned to TCL Interpreter. However, it is not quite clear what "Interactive behaviour" actually means and how it gets from simulation to automatic test equipment. IEEE 1687 is a "descriptive" standard, so there is no provision or limitation on the way the test routines will be executed and if and how they will interact with the System Under Test.