This type is used within the ICC_MEASUREMENT structure to indicate the standard observer.
typedef enum
{
StdObsUnknown = 0x00000000L, /* Unknown */
StdObs1931TwoDegrees = 0x00000001L, /* 2 deg */
StdObs1964TenDegrees = 0x00000002L /* 10 deg */
} ICCSTANDARDOBSERVER;