From OpenSCADAWiki
Moreover, unified templates are provided with the possibility of deep processing of input signals by defining in the field "Input processing procedure" for a procedure on the internal language JavaLikeCalc. And even more, in this procedure it is possible to expand the template data model of the parameter with auxiliary dynamic attributes, actually "hanging" on it the elements of the device object, starting from its main signal; that is without creating additional templates for this. Like this for appending an attribute for setting input manually: