# Sample working while() loop
    $sourceMetacodeLen = length $sourceMetacode;
    $sourceMetacodePos = 0;
    while ($sourceMetacodePos < $sourceMetacodeLen)
      {
        $recordLen = unpack( 'n',
                             substr $sourceMetacode,
                             $sourceMetacodePos,
                             2);
        $record = substr( $sourceMetacode,
                          $sourceMetacodePos + 2,
                          $recordLen - 2);

# not relevant to the example
#        $parse .= ${translate_record(\$record, $sourceMetacodePos, \@fonts)};

        $sourceMetacodePos += $recordLen;
      }