CHANNELTYPE

typedef enum _CHANNELTYPE
{
   ALPHA_CHANNEL = 0,
    RED_CHANNEL,
    GREEN_CHANNEL,
    BLUE_CHANNEL,
    CYAN_CHANNEL,
    MAGENTA_CHANNEL,
    YELLOW_CHANNEL,
    KEY_CHANNEL,
    GRAY_CHANNEL,
    BITMAP_CHANNEL,
    LIGHTNESS_CHANNEL,
    A_CHANNEL,
    B_CHANNEL
} CHANNELTYPE, *pCHANNELTYPE;

The CHANNELTYPE enumeration provides information about the type of the channel used to identify the alpha channels (extra channels) in the PSD files.