I hardly know any real facts about the topic, but I thought I'd share my thoughts for what it's worth.
How Windows stores Fonts
To my understanding, every font sub-type (as distinguished by the font characteristics) is stored in a single file on Windows (or, at least, it can be). This can lead to a bit of confusion. Let's look at an example.
As you can see, the Adobe Heiti Std R font (first on the second row) is visualized by single paper sheet with Abg on it. This is a single font, representing a single font file.
In contrast, the Arial font (last on the third row) is visualized by 3 sheets of paper. This means it's a font family consisting of multiple font files (which provide the same font but with differing characteristics).
However, this does not explain any _0
file names. Those exist for a different reason.
So where do the names come from?
Here is a directory listing I just did a minute ago:
C:\Windows\Fonts>dir aria*
2011-05-11 00:34 778,552 arial.ttf
2011-01-17 01:32 749,004 arialbd.ttf
2011-01-17 01:32 561,924 arialbi.ttf
2011-01-17 01:32 555,884 ariali.ttf
2006-07-14 12:01 173,936 ARIALN.TTF
2006-07-14 12:01 178,864 ARIALNB.TTF
2006-07-14 12:01 178,316 ARIALNBI.TTF
2006-07-14 12:01 179,368 ARIALNI.TTF
2002-11-18 18:44 23,275,812 ARIALUNI.TTF
9 File(s) 26,631,660 bytes
0 Dir(s) 163,335,311,360 bytes free
As you can see, no _0
files exist by default.
Now, if I copy arial.ttf
to my desktop, right-click it and select Install, the following dialog will pop up:
Now, you should click No! If you don't, this is the result:
C:\Windows\Fonts>dir aria*
2011-05-11 00:34 778,552 arial.ttf
2011-01-17 01:32 749,004 arialbd.ttf
2011-01-17 01:32 561,924 arialbi.ttf
2011-01-17 01:32 555,884 ariali.ttf
2006-07-14 12:01 173,936 ARIALN.TTF
2006-07-14 12:01 178,864 ARIALNB.TTF
2006-07-14 12:01 178,316 ARIALNBI.TTF
2006-07-14 12:01 179,368 ARIALNI.TTF
2002-11-18 18:44 23,275,812 ARIALUNI.TTF
2011-05-11 00:34 778,552 ARIAL_0.TTF
10 File(s) 27,410,212 bytes
0 Dir(s) 163,332,550,656 bytes free
Please note, that I now have a file called ARIAL_0.TTF
.
So, when you were importing those fonts, you might have brought some system fonts along. Obviously, Microsoft and I slightly differ in our definitions of the term "replace".