fontconfig "preferred" families and where to get more information

["Boncek, John" <jboncek hunter com>]

The fontconfig configuration files 60-latin.conf, 65-nonlatin.conf, and several others contain lists of preferred font families broken down by serif, sans-serif, and monospace.  Since there are therefore several lists of preferred sans-serif families, how are these different lists applied when a font description of say "sans 12" is used?  We have lots of cases of English mixed with Eastern languages, so I would like to really understand this.

 

That's one specific question.  More generally, does anyone know a book (or other information source) that goes into real detail on the fontconfig system from a user perspective?  The so-called "User's Manual" on the fontconfig website is a joke.