The GLYPHMETRICSFLOAT structure contains information about the placement and orientation of a glyph in a character cell.
typedef struct _GLYPHMETRICSFLOAT { // gmf   
    FLOAT      gmfBlackBoxX; 
    FLOAT      gmfBlackBoxY; 
    POINTFLOAT gmfptGlyphOrigin; 
    FLOAT      gmfCellIncX; 
    FLOAT      gmfCellIncY; 
} GLYPHMETRICSFLOAT; 
 The values of GLYPHMETRICSFLOAT are specified as notional units.
  Windows NT:  Use version 3.51 and later.
  Windows:  Use Windows 95 and later.
  Windows CE:  Unsupported.
  Header: Declared in wingdi.h.
OpenGL on Windows NT and Windows 95 Overview, Structures, POINTFLOAT, wglUseFontOutlines