this is not a normal (generator) ParameterObject: this is a Filter ParameterObject, which means that it transforms the output of another data stream (from a Texture). Filter ParameterObjects are used mostly in TextureClones, where you set up an object to transform the output of another TextureInstance.
in general, all arguments for ParameterObjects are comma separated. this remains true in this case. the confusion is in the presentation in the docs: i am showing the generator (a randomUniform PO) and then the transformer (orderBackward). orderBackward has no arguments but its name.
the best way to test out filter POs at first is to use the TPmap command. here i select a filter parameter object generate 20 events. the filter PO is orderBackward; the generator PO is ordered cyclic output of 5 values increasing values.
pi{}ti{} :: tpmap
select a library: Generator, Rhythm, or Filter. (g, r, f): f
number of events: 20
enter a Filter ParameterObject argument: ob
enter a Generator ParameterObject argument: bg,oc,(1,2,3,4,5)
basketGen, orderedCyclic, (1,2,3,4,5)
orderBackward
the graphic output shows first the source generator and then the transformed values.