All channel modes.

    #define SILC_CHANNEL_MODE_NONE         0x0000
    #define SILC_CHANNEL_MODE_PRIVATE      0x0001 /* private channel */
    #define SILC_CHANNEL_MODE_SECRET       0x0002 /* secret channel */
    #define SILC_CHANNEL_MODE_PRIVKEY      0x0004 /* channel has private key */
    #define SILC_CHANNEL_MODE_INVITE       0x0008 /* invite only channel */
    #define SILC_CHANNEL_MODE_TOPIC        0x0010 /* topic setting by operator */
    #define SILC_CHANNEL_MODE_ULIMIT       0x0020 /* user limit set */
    #define SILC_CHANNEL_MODE_PASSPHRASE   0x0040 /* passphrase set */
    #define SILC_CHANNEL_MODE_CIPHER       0x0080 /* sets cipher of the channel */
    #define SILC_CHANNEL_MODE_HMAC         0x0100 /* sets hmac of the channel */
    #define SILC_CHANNEL_MODE_FOUNDER_AUTH 0x0200 /* sets founder auth data */
    #define SILC_CHANNEL_MODE_SILENCE_USERS 0x0400 /* sets founder auth data */
    #define SILC_CHANNEL_MODE_SILENCE_OPERS 0x0800 /* sets founder auth data */
    #define SILC_CHANNEL_MODE_CHANNEL_AUTH 0x1000 /* channel auth (signature) */