Accessing metadata for specific letters

Question

• Do any font types store metadata about each letter?
• Or does Unicode provide any linguistic information about each symbol?
• Can this metadata be accessed in XeTeX?

Answer 1

The only things I know:

• Use \fontdimen to get the dimensions of the font. See TeX by Topic 4.3 Font information.

• Use \XeTeXglyphbounds to get the boundingbox of every glyph. See XeTeX Reference.

• Use \the\XeTeXcharclass ... to get the predefined character class of a glyph. You can distinguish CJK characters (class 1), CJK punctuations (class 2 and 3) from normal characters (class 0). That's all XeTeX knows. For example,

  \the\XeTeXcharclass`a    % 0
  \the\XeTeXcharclass`文   % 1
  \the\XeTeXcharclass`《   % 2, should not be at the end of a line
  \the\XeTeXcharclass`。   % 3, should not be at the beginning of a line
  

I don't think there are linguistic information of each symbol.