Explicit font & Implicit font 


In case there are so many font files:
Too many font definitions must be in vflibcap.
           e.g., TeX & X11 fonts
Maintenance of vflibcap is difficult.

Implicit font :
A font which is not listed in vflibcap.
Font file name is determined by font name & size parameters.
A font driver searches a font file to open.