What is file update_package on my SD card?

On the SD card of my 5803 I have a folder called recovery and in it is a file named update_package that is 635mb. I have dual recovery installed. I have been using twrp for several months successfully. Does anyone know what this file is? Can I remove it? It's dated June 3 which I think is the day that I installed the recovery. Is it left over from the original installation and not needed any more? Would love to know if anyone knows or if anyone is using dual recovery and doesn't have this file on the internal card so I can figure it out. Thanks


Sent from my Nexus 6