I was very surprised that I couldn't find this answer on Google.
I have seen someone access the default Apache index page (no index.html present, so it just shows the directory listing) with query string parameters. The URL they used was similar to:
http://example.com/?C=M;O=D It looks like O=D means "order = descending," since it reversed the order of the list, but I want to know what other parameters can be passed in, and what they mean. Is this documented somewhere? I couldn't find it.
"C=M;O=D" is the query string passed in to the URLs that are browseable. It's used to sort the files list.
O is the sort order, which can either be A or D for ascending and descending respectively.
C is for column name which is to be sorted. It can take the following values:
N - Name (file name) column
M - Last Modified column
S - Size column
D - might be for Description
You might want to have a look at this : https://httpd.apache.org/docs/2.2/mod/mod_autoindex.html
Just to add to the excellent accepted answer, if you want to change the default fancyindex file listing order, use the IndexOrderDefault directive.
For example:
Options +Indexes IndexOrderDefault Descending Date 
