[NTG-context] Obtaining the current font

Hi, in the gnuplot module the following macro is used for the TikZ terminal: \def\calculateGNUPLOTcharsize{% \global\GNUPLOThcharsize=1.05\fontcharwd\font`0% \global\GNUPLOTvcharsize=1.05\fontcharht\font`0% \global\advance\GNUPLOTvcharsize by 1.05\fontchardp\font`g% } What are \font`0 and font`g? AFAIK the backtick converts the character to the character code, which means it yields \font48 and \font103. The goal is to get the current font, right? Why is the current font width and height addressed with `0 and the depth with `g? And when do `0 and `g result in different values? In my tests they were always the same. Marco