The CHARRANGE structure specifies a range of characters in a rich edit control. This structure is used with the EM_EXGETSEL and EM_EXSETSEL messages.
If the cpMin and cpMax members are equal, the range is empty. The range includes everything if cpMin is 0 and cpMax is - 1.
typedef struct _charrange {
LONG cpMin;
LONG cpMax;
} CHARRANGE;