The directory tree is first partioned into subdirectories for the years of the mission (1984 - 1988). Under each year subdirectory are 365 subdirectories representing the days of year (DOY) within that year. Each DOY subdirectory contains the files for that day. Typically there will be a pair of High (Master) and Low (Summary) resolution file for up to two GOES satellites.
Access directory of Data Files here.