I'm learning how to use Coolite at the moment. I'm trying to use the Store element but I don't know what the ReaderID attribute of the JsonReader does?
Without checking specifically I would assume that the 'ReaderID' property has the same benefits as any 'ID' property, in that it gives a unique reference to the element.
This is often so that you can find it by the ID and perform functions directly upon a specific instance, rather than finding it by type or having to loop through all the items on a page and locate the specific instance you're after.