code: @Override
      public MatchStrength hasFormat(InputAccessor acc) throws IOException
      {
          if (!acc.hasMoreBytes()) {
              return MatchStrength.INCONCLUSIVE;
          }
          byte b = acc.nextByte();
          // Very first thing, a UTF-8 BOM?
          if (b == UTF8_BOM_1) { // yes, looks like UTF-8 BOM
              if (!acc.hasMoreBytes()) {
                  return MatchStrength.INCONCLUSIVE;
              }
              if (acc.nextByte() != UTF8_BOM_2) {
                  return MatchStrength.NO_MATCH;
              }
              if (!acc.hasMoreBytes()) {
                  return MatchStrength.INCONCLUSIVE;
              }
              if (acc.nextByte() != UTF8_BOM_3) {
                  return MatchStrength.NO_MATCH;
              }
              if (!acc.hasMoreBytes()) {
                  return MatchStrength.INCONCLUSIVE;
              }
              b = acc.nextByte();
          }
          if (b == '{' || Character.isLetter((char) b) || Character.isDigit((char) b)) {
              return MatchStrength.WEAK_MATCH;
          }
          return MatchStrength.INCONCLUSIVE;
      }
docs: Sub-classes need to override this method (as of 1.8)