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;

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