Hi,  RBSD looks like what we are calling any download that is a zip file and not a self installer. In this case it is the VIB file zip. I was not able to find what it is an acronym for.  
I'm surprised I can't find an answer to this by 'googling' - various downloads from Dell include this file format type (which is a zipped). Does anyone know what these are? Here is an example: www.dell.com/.../DriversDetails [URL]  
What is RBSD File Type?