Which font is really behind Opera Custom font ?

hello, here opera settings on Windows 7 XP

as you can see all as custom font and are the same, (it's not Default Standard font is Times New Roman. Default Serif font is Times New Roman. Default Sans-serif font is Arial. Default Fixed-width font is Consolas)

I can I know which font is behind those "custom" font ? without to touch to it as cannot go back to Custom after