The ENPROTECTED structure contains information associated with an EN_PROTECTED notification message. A rich edit control sends this notification when the user attempts to edit protected text.
typedef struct _enprotected { 
    NMHDR nmhdr; 
    _WPAD _wPad1; 
    UINT msg; 
    _WPAD _wPad2; 
    WPARAM wParam; 
    LPARAM lParam; 
    CHARRANGE chrg; 
} ENPROTECTED;