private static function initExtnPatterns() { // One-character symbols that can be used to indicate an extension. $singleExtnSymbolsForMatching = "xx##~~"; // For parsing, we are slightly more lenient in our interpretation than for matching. Here we // allow a "comma" as a possible extension indicator. When matching, this is hardly ever used to // indicate this. $singleExtnSymbolsForParsing = "," . $singleExtnSymbolsForMatching; self::$EXTN_PATTERNS_FOR_PARSING = self::createExtnPattern($singleExtnSymbolsForParsing); self::$EXTN_PATTERNS_FOR_MATCHING = self::createExtnPattern($singleExtnSymbolsForMatching); }