At the risk of getting into more trouble in this thread, I do not think that this will work out well for you. There can be very good reasons to concatenate strings into a single hash key, but once we are talking about 5 FIVE dimensions, this doesn't make sense. I apologize for not reading this thread carefully from the beginning.

sounds like you need an Array of Hash.

each hash like:
start => "some start date",
end   => "some end date",
parm1 => "some data1",
parm2 => "some data2",
parm3 => "some data3",
[download]