The 3000 series has a range of Mixed Signal Oscilloscopes (MSO) http://www.picotech.com/usb3-oscilloscope-logic-analyzer.html
These device have 2/4 analogue channels and 16 digital channels.
Certain programming languages such as LabVIEW cannot support C style callbacks, which streaming requires to avoid data corruption during capture.
The wrapper dll contains the callback and some set up function to make streaming easier to use.
Please have a look at http://www.picotech.com/support/topic14301.html
Hopefully this clears up some confusion.