k.. this's kinda weird coz I posted the question and now I'm posting the answer too
took a while to figure this out.
"C=M;O=D" is the query string passed in to the URLs that are browsable. 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's 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, but havent tried it
for example:
http://somesite/folder/?C=N;O=A
would return the files list sorted by their file names in ascending order
not sure if C and O take other values.
neither do I know if this's server specific.
I'd be glad if someone could clarify that.