The general rule is that PowerFactory provides access within DSL to variables belonging to a certain network element only if they are marked correspondingly in the Variable Selection dialog, under the corresponding page (either RMS-Simulation or EMT-Simulation) as IN or OUT. The use of the signals is "as declared", hence a user should not use an "IN" variable as an output or vice-versa. To the general rule, there is only a handful of undocumented exceptions in the form of calculation parameters: e.g. busbar voltage components, synchronous generator apparent power (c:sgnn) and other. Unfortunately there is no compiled list of these exceptions. The recommended procedure is then to use separate DSL parameters that will duplicate the specific element parameters intended to use from the network element.