Log csv file naming format?

I use HWINFO frequently for its powerful csv logging function. However, I am confused over the naming format of those log files, as I need a reliable way to identify the log file's generation sequence (which file is the latest one) without reading the file (that is, purely from filename). The current pattern I'm seeing is HWiNFO_LOG_xxxxxxxxx.CSV where the x are a string of numbers that varies in length. I thought it is the ms since UNIX but after googling it is apparently not. So I am wondering what exactly do these numbers represent, and whether they can be used as a sole indication of which log is the latest one.
So it is ms since system boot or computer power on, which means it will be always increasing, and will reset after a reboot?
Hi, I just found out today that HWINFO has been naming the log files with a negative sign (-) in front of the millisecond number. This can be reproduced on multiple devices but not on my own. Any explanation for this?

Ok thanks.
Another logging file question. The degree symbol has been causing problems for me because for some reason due to the encoding the symbol cant display properly on other systems if it was generated on mine, and my system also cannot display other ppl's files. Is there any way to force the encoding to a specific codec that supports the degrees symbol (say, utf-8)?
An example of the csv file opened using notepad:
The file on another system even gave a differnet character (different from the one in the screenshot), so it is kind of random for me
This is currently encoded depending on how the character set for Non-Unicode programs is set it Windows. If you change this to UTF-8, the result in CSV should be same.