typedef enum { ... } SilcTaskType;

    SILC has three types of tasks, non-timeout tasks (tasks that perform
    over file descriptors), timeout tasks and generic tasks (tasks that
    apply to every file descriptor). This type is sent as argument for the 
    task registering function, silc_schedule_task_add.

    typedef enum {
      /* File descriptor task that performs some event over file descriptors.
         These tasks are for example network connections. */
      SILC_TASK_FD           = 0,
    
      /* Timeout tasks are tasks that are executed after the specified 
         time has elapsed. After the task is executed the task is removed
         automatically from the scheduler. It is safe to re-register the
         task in task callback. It is also safe to unregister a task in
         the task callback. */
      SILC_TASK_TIMEOUT,
    
      /* Generic tasks are non-timeout tasks and they apply to all file 
         descriptors, except to those that have explicitly registered a 
         non-timeout task. These tasks are there to make it simpler and faster 
         to execute common code that applies to all connections. These are,
         for example, receiving packets from network and sending packets to
         network. It doesn't make much sense to register a task that receives
         a packet from network to every connection when you can have one task
         that applies to all connections. This is what generic tasks are for.
         Generic tasks are not bound to any specific file descriptor, however,
         the correct file descriptor must be passed as argument to task
         registering function. */
      SILC_TASK_GENERIC,
    } SilcTaskType;