How is defined the data type FXPT2DOT30 in the BMP file structure? - bmp

Question

The type FXPT2DOT30 appears in defining the struct CIEXYZ for BMP files,
according to the definition provided by Microsoft:
http://msdn.microsoft.com/en-us/library/windows/desktop/dd371828(v=vs.85).aspx
However, I cannot found the exact definition of FXPT2DOT30 anywhere.
Which is its precise definition?
What kind of data is supposed to hold?

Answer 1

#RobinGreen provided a link:
There it is the answer to my question:
[...] FXPT2DOT30 [...] which means that they are interpreted as fixed-point values with a 2-bit integer part and a 30-bit fractional part.

Answer 2

According to fileformat.info here is an unpacked version of the BITMAPV4HEADER structure. The fields between CSType and GammaRed correspond to the CIEXYZTRIPLE bV4Endpoints in BITMAPV4HEADER.
typedef struct _Win4xBitmapHeader
{
DWORD Size; /* Size of this header in bytes */
LONG Width; /* Image width in pixels */
LONG Height; /* Image height in pixels */
WORD Planes; /* Number of color planes */
WORD BitsPerPixel; /* Number of bits per pixel */
DWORD Compression; /* Compression methods used */
DWORD SizeOfBitmap; /* Size of bitmap in bytes */
LONG HorzResolution; /* Horizontal resolution in pixels per meter */
LONG VertResolution; /* Vertical resolution in pixels per meter */
DWORD ColorsUsed; /* Number of colors in the image */
DWORD ColorsImportant; /* Minimum number of important colors */
/* Fields added for Windows 4.x follow this line */
DWORD RedMask; /* Mask identifying bits of red component */
DWORD GreenMask; /* Mask identifying bits of green component */
DWORD BlueMask; /* Mask identifying bits of blue component */
DWORD AlphaMask; /* Mask identifying bits of alpha component */
DWORD CSType; /* Color space type */
LONG RedX; /* X coordinate of red endpoint */
LONG RedY; /* Y coordinate of red endpoint */
LONG RedZ; /* Z coordinate of red endpoint */
LONG GreenX; /* X coordinate of green endpoint */
LONG GreenY; /* Y coordinate of green endpoint */
LONG GreenZ; /* Z coordinate of green endpoint */
LONG BlueX; /* X coordinate of blue endpoint */
LONG BlueY; /* Y coordinate of blue endpoint */
LONG BlueZ; /* Z coordinate of blue endpoint */
DWORD GammaRed; /* Gamma red coordinate scale value */
DWORD GammaGreen; /* Gamma green coordinate scale value */
DWORD GammaBlue; /* Gamma blue coordinate scale value */
} WIN4XBITMAPHEADER;

Answer 3

From gdiplus.h:
typedef long FXPT2DOT30, FAR *LPFXPT2DOT30;
typedef struct tagCIEXYZ
{
FXPT2DOT30 ciexyzX;
FXPT2DOT30 ciexyzY;
FXPT2DOT30 ciexyzZ;
} CIEXYZ;