code: public static boolean isSeparateChecksumBlockFilename(String name) {
      if (isBlockFileName(name) && name.indexOf('.') < 0
          && name.indexOf('_', BLOCK_FILE_PREFIX.length()) < 0) {
        return true;
      } 
      return false;
    }
docs: Determine whether the data file is for a block of non-inline checksum
  The file name is of this format:
  blk_<blk_id>
  @param name
  @return