typedef enum { ... } SilcStringprepFlags;

    Flags that change how the strings are prepared with silc_stringprep.

    typedef enum {
      SILC_STRINGPREP_NONE               = 0x00,  /* No flags */
      SILC_STRINGPREP_ALLOW_UNASSIGNED   = 0x01,  /* Allow unassigned characters
                                                     without returning error. */
    } SilcStringprepFlags;