From OpenSCADAWiki
Logical (Prm)
Given of high intelligence of the data sources, in face of the industrial controllers of Siemens S7-200,300,400,1200, the type parameter objects are executed on the basis of templates. This approach allows you not to be restricted to a rigid list of types of parameters, which also restricts the capabilities of the controllers, but to allow the user to create the required types of parameters independently, or to use libraries of earlier developed types of parameters — templates.