The columns of the files are the Day of the Year (DOY), while the rows are time of day (TOD). As the files are 10-minute medians, there are 144 values per day. So 0 is 00:00, 1 is 00:10 and so on.
The key is "data"

example structure:

		0	1	2	3	...	0 means 1st January, 1 means 2nd January...
0 means 00:00 value   value   value   value	...	
1 means 00:10 value   value   value   value	...	
2 means 00:20 value   value   value   value	...
3 means 00:30 value   value   value   value	...
...
