Extend XML attribute access

[arcanefoam]

Currently the driver uses the XML driver implementation for property access, i.e. prefix based attributes. However JSON supports list values, which do not exist in XML. Perhaps the JSON driver could extend the XML property access to provide an additional prefix, perhaps "l_" (or "c-") to indicate the the attribute returns a list of elements.

[arcanefoam]

Never mind, XML driver does support "c_" prefix for collectios