         else if (strcmp( argv[i], "-a" ) == 0 ||
                  strcmp( argv[i], "--ascii" ) == 0)  // ascii format
         {
-            format = ASCII;
+            format = ASCII_FORMAT;
         }
         else if (strcmp( argv[i], "-p2" ) == 0 ||
                  strcmp( argv[i], "--packed-2" ) == 0)  // 2-bits packed
         {
-            format = PACKED2;
+            format = PACKED2_FORMAT;
         }
         else if (strcmp( argv[i], "-p4" ) == 0 ||
                  strcmp( argv[i], "--packed-4" ) == 0)  // 4-bits packed
         {
-            format = PACKED4;
+            format = PACKED4_FORMAT;
         }
         else if (strcmp( argv[i], "-i" ) == 0 ||
                  strcmp( argv[i], "--idx" ) == 0)       // index file

    const char* idx_name    = NULL;
    bool  forward           = true;
    bool  reverse           = true;
    Format format           = ASCII;
    io::QualityEncoding qencoding = io::Phred33;

    for (int i = 0; i < argc - 2; ++i)

    if (argc < 2)
    {
        log_info(stderr, "nvExtractReads [options] input output\n");
        log_info(stderr, "  extract a set of reads to a plain ASCII_FORMAT or packed file with one read per line (.txt)\n\n");
        log_info(stderr, "options:\n");
        log_info(stderr, "  --verbosity\n");
        log_info(stderr, "  -F | --skip-forward          skip forward strand\n");
        log_info(stderr, "  -R | --skip-reverse          skip forward strand\n");
        log_info(stderr, "  -a | --ascii                 ASCII_FORMAT output\n");
        log_info(stderr, "  -p2 | --packed-2             2-bits packed output\n");
        log_info(stderr, "  -p4 | --packed-4             4-bits packed output\n");
        log_info(stderr, "  -i  | --idx string           save an index file\n");
